• Journal of fish pathology
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• v.31 no.2
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• pp.101-107
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• 2018

Quantitative analysis of a myxosporean parasite, Parvicapsula sp. in internal organs (kidney, intestine, spleen, brain and liver) from non-emaciated (farm-A) or emaciated (farm-B and farm-C) olive flounder Paralichthys olivaceus were performed by real-time PCR. The highest DNA copy number ($1.7{\times}10^7copies/mg$ tissue) was detected in kidney of the emaciated olive flounder from farm-C, while the DNA copy number was below detection limit in all the organs of the olive flounder from farm-B. There was not positive result in all of organs from olive flounder in farm-A. PCR and histopathological analysis were also performed using the same specimen and showed same results as those by real-time PCR.

• The Journal of Fisheries Business Administration
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• v.42 no.3
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• pp.79-93
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• 2011

Water temperature of Oliver flounder farm affects Oliver flounder growth and mortality rate. In laboratory experimental tanks, optimal water temperature was $22.5^{\circ}C$($21{\sim}24^{\circ}C$) and cultivatable water temperature was $12{\sim}28^{\circ}C$. The purpose of this study is to identify applicable and useful water temperature of Oliver flounder farm in case of actual farming. The data applied in the analysis was collected from Jeju island. In the study, various analytical methods including productivity analysis, regression analysis, statistical analysis were conducted for 13 Oliver flounder culture farms. The result of analysis can be summarized as follows : First, growth rate on the Oliver flounder culture farms was related to mean of water temperature, variation of water temperature and low water temperature. Second, survival rate on the Oliver flounder culture farms was related to mean of water temperature. In case of including Oliver flounder stocking density, defined as the surface area of Oliver flounder per $m^2$ of water surface area, survival rate strongly related to mean of water temperature, variation of water temperature, cultivating capability and stocking density. Third, production weight per $m^2$ of water surface area was strongly related to mean of water temperature, low water temperature and cultivating capability. Growth rate and survival rate was analyzed into mediate variable character.

• The Journal of Fisheries Business Administration
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• v.40 no.3
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• pp.189-205
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• 2009

This study is aimed to analyze the economic feasibility comparison of the extruded pellets and moist pellets on the Oliver flounder culture farms in Jeju Island. In order to do this, we selected 2 farms (M and S farms) in Jeju Island as a sample. In the study, various analyses including productivity analysis, cost structure analysis, profitability and economic feasibility analysis by feed type were conducted for two sample farms of Oliver flounder culture. The results of economic analysis by feed type on the Oliver flounder culture can be summarized as follows; First, there were not significant differences in productivity by feed type. Second, results of the profitability analysis on farm M by feed type showed the profitability was estimated to be 15.52% and 9.83% in EP and MP, respectively. In addition, the profitability of farm S was estimated to be 28.37% and 33.72% in EP and MP, respectively. Third, results of the economic analysis on farm M by feed type indicated that an internal rate of return(IRR) was 8% and 7% and a benefit-cost ratio was shown to be 1.64 and 1.11 in EP and MP, respectively. Furthermore, the economic analysis of farm M by feed type showed that an IRR was 19% and 24% and a benefit-cost ratio was calculated to be 1.4 and 1.51 in EP and MP, respectively. In summary, it is especially emphasized that economic valuation is not related to feed types (EP and MP). Finally, in order to improve the economic feasibility, it should be more focused on the efficient business management of the Oliver flounder aquaculture.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.58 no.1
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• pp.59-67
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• 2022

This study assessed the levels of water qualities and microbials contamination of inland olive flounder farms in Jeju in the summers from 2015 to 2017. Three farms (A-C) located in a concentrated area using mixing coastal seawater and underground seawater and one farm (D) located in an independent area using only coastal seawater were selected. Total ammonia nitrogen (TAN) reached a maximum of 0.898 ± 1.024 mg/L as N in the coastal seawater of A-C, which was close to the limit of the water quality management goal of the fish farm. TAN in the influent from A-C was up to three times higher than that of D, so that the discharged water did not spread to a wide range area along the coast and continued to affect the influent. TAN of the effluent in A-C increased by 2.7-4.6 times compared to the influent, resulting in serious self-pollution in the flounder farm. Heterotrophic marine bacteria in the influent of A-C was about 600 times higher than D, and the discharge of A-C was increased by about 30 times compared to the influent.

• The Journal of Fisheries Business Administration
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• v.42 no.2
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• pp.85-96
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• 2011

Oliver flounder population density affect Oliver flounder growth and mortality rate. In laboratory pilot experiment, Oliver flounder growth rate is inversely proportional to stocking density. But previous study has not proved external validity. This study is aimed to analyze the effect of stocking density on the Oliver flounder culture farms in Jeju Island. In order to do this, I selected 13 farms in Jeju island as a sample. In the study, various analytical methods including productivity analysis, regression analysis, statistical analysis were conducted for 13 Oliver flounder culture farms. The result of analysis can be summarized as follows. First, in case of the Oliver flounder culture farms, Bertalanffy equation is not applicable to the Oliver flounder growth. Second, the Oliver flounder stocking density, defined as the surface area of Oliver flounder per $m^2$ of water surface area, is preferred to density definition defined as the weight of Oliver flounder per $m^2$ of water surface area on the Oliver Flounder Culture Farms case. Third, growth rate and production weight on the Oliver flounder culture farms are inversely proportional to stocking density on spearman rank correlation test. When extensive comparable biological and culture condition data become available, analysis model can be easily modified to yield more accurate results.

• Journal of Fisheries and Marine Sciences Education
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• v.21 no.4
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• pp.556-561
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• 2009

This study was conducted to evaluate the laboratory formulated extruded pellet (EP) for olive flounder Paralichthys olivaceus in the East Sea. Three replicate groups of 3,200 fish per each tank (initial weight of $28.1{\pm}0.2g$) were fed one of the two EPs (EP and CEP) and Moist pellet (MP) for 16 months in a commercial farm (Pohang, Korea). Survival was not significantly affected by experimental diets (P>0.05). Weight gain and specific growth rate of fish fed the EP were not significantly different from those of fish fed the MP, but that of fish fed CEP was significantly lower than that of fish fed EP and MP (P<0.05). Feed efficiency and protein efficiency ratio of fish fed the EP was significantly higher than those of fish fed MP (P<0.05), but not significantly different from those of fish fed CEP (P>0.05). The Contents of moisture, crude protein and crude lipid in the dorsal muscle were not significantly different among all groups (P>0.05). These results clearly indicated that the laboratory formulated extruded pellet used in this study can be developed to replace the moist pellet without affecting any growth performance of olive flounder in the commercial farm feeding trail.

• Fisheries and Aquatic Sciences
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• v.20 no.8
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• pp.16.1-16.8
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• 2017

The exportation of cultured olive flounder (Paralichthys olivaceus) in Korea has been recently decreasing due to the infections with a myxozoan parasite Kudoa septempunctata, and there is a strong demand for strict food safety management because the food poisoning associated with consumption of raw olive flounder harbouring K. septempunctata has been frequently reported in Japan. The life cycle and infection dynamics of K. septempunctata in aquatic environment are currently unknown, which hamper establishment of effective control methods. We investigated sea water and marine invertebrates collected from olive flounder farms for detecting K. septempunctata by DNA-based analysis, to elucidate infection dynamics of K. septempunctata in aquaculture farms. In addition, live marine polychaetes were collected and maintained in well plates to find any possible actinosporean state of K. septempunctata. The level of K. septempunctata DNA in rearing water fluctuated during the sampling period but the DNA was not detected in summer (June-July in farm A and August in farm B). K. septempunctata DNA was also detected in the polychaetes Naineris laevigata intestinal samples, showing decreased pattern of 40 to 0%. No actinosporean stage of K. septempunctata was observed in the polychaetes by microscopy. The absence of K. septempunctata DNA in rearing water of fish farm and the polychaetes N. laevigata intestinal samples during late spring and early summer indicate that the infection may not occur during this period. N. laevigata was suspected as the possible alternate invertebrate host of K. septempunctata, but the actinosporean stage was not found by well plate method and further studies will be necessary. This research provides important baseline information for understanding the infection dynamics of K. septempunctata in olive flounder farms and further establishment of control strategies.

• Journal of Fisheries and Marine Sciences Education
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• v.22 no.4
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• pp.529-536
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• 2010

This study was conducted to effect of extruded pellets (EPs) and moist pellet (MP) diet on growth and fish health parameters in farm cultured olive flounder Paralichthys olivaceus. Two replicate groups of 2,600 fish per each tank (initial weight of $30.1{\pm}0.2$ g) were fed one of the three EPs (EP1, EP2 and CEP) and one MP for 13 months. In field feeding experiment conducted in commercial flounder farm, survival, growth (30-600 g) and condition factor of fish fed experimental EP1 and EP2 were comparable to those of fish fed MP, but considerably higher feed efficiency and protein efficiency ratio were observed in fish fed experimental EPs. Viable cell counts from diet and water from MP diet were considerably higher than those from EP diet, and lysozyme activity from EP diet was higher than that from MP diet. GOT and GPT of fish fed the EP diet were considerably lower than those from MP group, but total protein and glucose concentration of fish fed the EP groups were not significantly different from that of fish fed the MP. Therefore, these results strongly suggest that EP diets could be developed to replace MP diet without adverse effects on growth performance and to enhance the immunity and protective ability of olive flounder against fish disease such as Vibro, Edwardsiella and Strptococcus.

• Journal of fish pathology
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• v.28 no.3
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• pp.165-169
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• 2015

Occurrence of Scuticociliatosis in olive flounder farm of Jeju was monitored from 2007 to 2014. As a result, 23.8~36.4% of referred samples were diagnosed as Scuticociliatosis. Based on fish size, the highest incidence (50.5%) was found in fish with size of 10~20 cm.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.3
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• pp.746-759
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• 2016

In this study, we monitored the status of marine environment of olive flounder, Paralichythys olivaceus, culture ground in Jeju-do, Republic of Korea. It reported the consumption of raw olive flounder meat containing of Kudoa, Kudoa septempunctata, could induce vomitting and diarrhea in Japan. The Kudoa is a new mycosporean species, researchers found Kudoa from the muscles of olive flounder cultured at western Japan and imported from Jeju-do. We choose two Kudoa positive farms and two negative farms in the mid of concern about the relation between Kudoa and habitat. We found two marine invasive species at the water-pumping seabed at one of the Kudoa positive farm. The concentration of pH and DO at on-growing flounder farms showed the decreasing pattern along side the raceway (influent sea waters > on growing sea waters > outfluent sea waters). The TN and TP values increased gradually following to the raceway (influent sea waters < on growing sea waters < outfluent sea waters). The concentration of COD and SS were in the range of $0.100-2.581mg{\cdot}L^{-1}$, $1.00-12.70mg{\cdot}L^{-1}$, respectively. The calculated residence time was 4hr 32minutes at F1, 11hr 21minutes at F2, and 9hr 50minutes at F3, respectively. It was calculated same distance of 4 km away from effluent pipes. Although direct relation between Kudoa and marine environment could not define well based on this study result, the more studies on marine environmental stressors for olive flounder are required to conduct as a reliable method including socio-economic group and environmental group.