• Journal of fish pathology
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• v.36 no.2
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• pp.379-388
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• 2023

Experiments were performed to investigate hypoxia tolerance with body size of red seabream (Pagrus major) at 24℃. The rate of oxygen consumption was measured at an interval of 10 min using automated intermittent-flow respirometry. The weight-specific standard metabolic rate (SMR, mg O₂ kg^-1hr^-1) and critical oxygen saturation (S_crit, % air saturation) of the fish were measured under normoxic condition and progressive hypoxia with 0.6-786 g of fish weight (W), respectively. SMR typically decreased with increasing body weight based on SMR=351.59·W^-0.195 (r²=0.934). S_crit was higher in larger fish than those of smaller fish in the range of 17.3-24.4%. The result of this study suggests that the smaller seabream can withstand in hypoxic waters better than the larger ones.

• Journal of Aquaculture
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• v.11 no.2
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• pp.203-212
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• 1998

As seed production program is growing prosperously in various fishes in southern Korea, disease problems in larval and juvenile stages have emerged as a new research object. The following results were obtained from investigation about environmental factors related to mass mortalities of young Kinki red seabream, Pagrus major in process of artificial seedling production. Total length of red seabream larvae hatched was 2.93mm, and became 18.83~20.12mm at day 40. The first noticeable mortality of red seabream larvae (7.98~9.37mm) occurred in 25~30 day-old fish with the survival rates of 59.8~60.3%. Thereafter the mortality of larvae decreased, survival rate was 20.5~25.45% in day 40. After 20~30 days, the quality of pond water was bellow II class. During the experimental period COD, $PO_4$-P, $NO_2$-N, $NO_3$-N and $NH_$-N increased up to 3, 7, 34, 6 and 8 times, respectively, compared to initial ones. The number of viable bacteria in pond water and seabream larvae were $6.3{\times}10^6$~$2.3{\times}10^7$ cfu/ml, 4.3~$7.4{\times}10^6$ cfu/g in day 25, respectively. Among the isolated bacteria from the diseased red seabream in day 25, Vibrio spp. was considered to be the causative organism. External symptoms of this disease were floated, spined near the surface and inflated abdomen. When the isolated strain of the Vibrio was bathed to seabream larvae, $LD_50$ of seabream larvae was over $10^6$ cfu/ml of Vibrio spp.

• Korean Journal of Ichthyology
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• v.29 no.1
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• pp.41-51
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• 2017

To understand the application in farm for the fish aquaculture, we investigated biological and pathological traits on red sea bream Pagrus major which were reared in each copper-alloy net cage and the synthetic fiber net cage for 9 months. Two groups of cage were made and set in Yokji-eup, Tongyoung, Gyeongsangnam-do in size of 25 m in diameter and 10 m of depth. Survival rate of the red sea bream in the rearing copper-alloy net cage and synthetic fiber cage showed 99.75% and 99.70% respectively, there was no significant difference. Daily weight growth rate in each net was shown to 2.13 g/day and 1.65 g/day. Health analysis by blood composition analysis showed a favorable result in the copper-alloy net cage rather than in the synthetic fiber net. Bioaccumulation of heavy metal such as Cu and Zn especially in gonad was higher than other organ. Bioaccumulation of Cu and Zn in the muscle was lower compared to the permitted standard for food safety. Pathogenic infection test discovered Microcotyle tai for parasite, V. alginolyticus and other five species for bacteria. But there was a little bit difference of bacteria infection in copper-alloy net cage and copper-alloy net cage is expected to be has antibacterial effect. Thus, copper-alloy net cage can be applied to farm considering its system stability, recycling, antibiosis and food safety.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.575-584
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• 2021

The critical low temperature and response of the behavioral tolerance of red sea bream Pagrus major fingerlings were determined using the continuous behavior monitoring system (CBMS). The behavior of the experimental organisms was observed by decreasing the water temperature by 2.0℃ and 4.0℃ every 12 hours and 24 hours in the range of 8.0-20.0℃. An unstable behavior pattern was observed in red seabream fingerlings exposed to water temperatures below 12.0℃, in which the swimming activity decreased and repeatedly stopped, regardless of the exposure time and water temperature fluctuation. The swimming ability of the organisms exposed to 8.0-10.0℃ decreased sharply, and the behavior of staying at the bottom of the test tank was observed. Only 50 % of the organisms survived due to the low-temperature stress, and all individuals died within six hours after the cold shock. In addition, the behavior index (BI) decreased rapidly, and the amplitude change of the coefficient of variation (CV) was found to have a greater variation than the other water temperatures (p<0.05). Low-temperature stress of red sea bream is promoted at 12.0℃, and it is interpreted as the tolerance limit, which can induce a sublethal response of the organisms exposed to cold shock of 8.0-10.0℃.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.5
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• pp.400-404
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• 2004

Growth performances of the selected and the non-selected red sea bream (Pagrus major) lines were evaluated up to marketable size. The offspring were mass-produced either from the selected line (the fourth generation of broods from mass selection) or the non-selected line (the second generation of wild broods). Early (59 to 103 days old, trial I) and late growth performances (4 to 24 months old, trial II) were evaluated based on communal rearing in land-based tanks and sea cages, respectively. In trial I, the selected line exhibited significantly higher values in both weight gain (WG) and specific growth rate (SGR) when compared to those observed in the non-selected line (P<0.05). In trial II comprising of three growth phases (4-9, 9-16 and 16-24 months old), selected line showed only slightly improved in WG and SGR at the beginning two growth phases (4-9 and 9-16 months old) (P>0.05), however, displayed significantly higher values at the last growth phase (16-24 months old) (P<0.05). Overall WG and SGR throughout the experiment (4-24 months) were also significantly higher in the selected line than the non-selected line (P<0.05). Consequently, mean body weight of the selected line at 24 months old was 1.4-fold (40.8{\%}\;increased) as compared to that of the non-selected line. This present result indicates that mass selection of this species against the growth traits might be quite effective, and the present advance has important Implication in the productivity enhancement of red sea bream aquaculture.

• Proceedings of the Korean Aquaculture Society Conference
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• 2006.05a
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• pp.340-341
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• 2006

• Proceedings of the Korean Aquaculture Society Conference
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• 2005.05a
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• pp.44-45
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• 2005

• Proceedings of the Korean Aquaculture Society Conference
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• 2004.05a
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• pp.158-159
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• 2004

• Proceedings of the Korean Aquaculture Society Conference
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• 2004.05a
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• pp.126-127
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• 2004

• Fisheries and Aquatic Sciences
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• v.4 no.3
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• pp.130-137
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• 2001

In the present study, the locomotor and feeding activities of single red sea bream, Pagrus major were simultaneously investigated to examine the existence of such dual behaviour. Seven red sea bream of 13cm body length on average were placed individually in 35L tanks equipped with an infrared sensor and a newly developed demand-feeding device. Fish were exposed to a light: dark 12: 12h cycle and constant darkness (DD) to study endogenous rhythmicity. Under LD 12: 12 h, the daily pattern of behaviour differed between individual fish; some red sea bream were diurnal and others were nocturnal. Futhermore, some of them displayed an extraordinary flexibility in phasing because they were dark active but light feeding, and vice versa. Under DD, red sea bream showed free-running rhythms for locomotor activity and feeding. These results indicate that the type of phasing of locomotor activity did not necessarily decide the feeding phase; much of this is explained by the fact that red sea bream were demand-fed. Flexibility in phasing and a certain degree of independence between locomotor and feeding activities could be seen as an adaptative response of the highly adaptable circadian rhythms of fish.