• Journal of Aquaculture
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• v.11 no.2
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• pp.261-269
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• 1998

The harpacticoid copepod, Tigriopus japonicus is one of the important zooplankton as a live food the production of marine fish fry. This reserch was carried out to investigate the culturing method and dietary value of T. japonicus. The reproduction of this copepod was analysed in the culturing systems (tne opened and the closed systems) and the surface area of the substate plates for the mass culture. Survival rate of the mature female and the number of nauplii produced per female for two day was higher in the open culturing system than in the close system. However, the result of survival rate of the nauplius was reversed. Larger surface area of the culturing vessel accommodated higher density of this bentic copepod. In polyculture of T. japonicus and rotifer (B. plicatilis), growth of T. japonicus seems to be dependent on the rotifer density. But rotifer seems to be independent on the copepod. With regard to dietary value, this copepod is better than Artemia nauplius for the larvae of red sea bream and tiger puffer which feed by picking. However, it is inadequate for bottom fish larvae as flounder.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.3
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• pp.337-345
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• 2015

To investigate the causes of emaciation in cultured olive flounder Paralichthys olivaceus in Korea. We performed histological examinations and polymerase chain reaction (PCR) with a new primer set. In most cases, the most severe emaciation was observed in the abdominal area Using PCR on extracted livers, kidneys, spleens, gills, brains, and intestines, we found that areas around the kidneys and intestines were as almost always positive. In significantly emaciated fish, PCR was positive in all internal organs except the gills. In addition, the homology of 812-bp nucleotide sequences of the 28S rRNA gene was more than 99% in emaciated fish. Partial homology with Myxobolus spp. and Cystodiscus axonis, whose data were obtained from GenBank was 86% and 88%, respectively. Histological examinations detected spores in kidneys and intestines but not in other organs. We also performed cohabitation experiments to determine whether infections could be exchanged among species or only within species. Uninfected olive flounder and red sea bream, Pagrus major, cohabitating with emaciated olive flounder showed 100% and 0% cumulative mortality, respectively. Thus the cause of emaciation in cultured olive flounder of Korea is likely due to a new parasite.

• Journal of Aquaculture
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• v.6 no.4
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• pp.285-293
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• 1993

Gynogenetic diploid of olive flounder, Paralichthys olivaceus were induced by cold shock to fertilized eggs with red sea bream, Paragus major sperm that had been genetically inactivated with 4,800 ergs/$mm^2$ ultraviolet (UV) rays. Cold shock to the eggs at $2^{\circ}C$ for 45 minutes proved to be optimum condition to retain the second polar body. At this treatment, hatching rates of normal fry obtained were more than $33.8\%$. No different growth rates were observed up to 200 days after hatching between control and gynogenetic diploid offsprings. However, body weights of gynogenetic diploids were significantly heavier than that of control 300 days after hatching (p> 0.05). A proportion of female in gynogenetic diploid was significantly higher than that in the control (p< 0.01).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.4
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• pp.259-268
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• 2004

Keeping qualities of crude proteases (CP) and fractionated proteases (FP) sedimenting with $30\~80{\%}$ ammonium sulfate from four kinds of fish viscera as a seafood processing waste were examined. Azocaseinolytic activlties (pH 6 and 8) of CP from anchovy (Engraulis japonica), mackerel (Scomber japonicus), bastard flatfish (Pararlichthys olivaceus) and red sea bream (Chysorphys major) were stable without activity loss at $4^{\circ}C$ for 7 months. Activities of NaCP (CP containing $30{\%}$ sodium chloride) on azocasein were approximately $30{\%}$ lower than those of CP. FP activities Increased 3.4-16.1 folds compared to those of CP and NaCP Powdered crude protease (PCP) and fractionated and powdered protease (FPP) containing various sugars (lactose, sucrose, glucose and dextrin) were prepared by freeze drying. Activities of PCP and FPP containing sucrose were higher and more stable than those of PCP and FPP containing other sugars at $30^{\circ}C$ for whole keeping periods. PCP and FPP from mackerel viscera showed the highest proteolytic activity among four kind of fish vlsceras. The Optimum conditions and stabilities of FPP from mackerel viscera were pH 9 and $50^{\circ}C$, and pH 5-10 and $20-45^{\circ}C$, respectively. The results of this study suggest that FPP from seafood processing waste may be used as processing aids.

• Journal of fish pathology
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• v.22 no.3
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• pp.283-291
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• 2009

This study was conducted to evaluate the effects of a commercial extruded pellet (EP) and raw fish moist pellet (MP) diet on disease prevalence and serum chemistry of olive flounder Paralichthys olivaceus grown in two commercial-scale aquaculture farms from July to December in 2008. The contents of serum GOT, GPT and glucose in fish fed EP diet (EP group) were higher than those of fish fed the MP diet (MP group). There were no distinct differences in survival rates and mean detection rates of fish pathogens among fish group fed the experimental diets. However, the mean detection rate of fish pathogens in MP group was higher than that of EP group from July to October which are high water temperature season. The dominant pathogens isolated in EP group were Dactylogyrus sp., E. tarda and red sea bream iridovirus (RSIV). On the other hand, Trichodina sp., Streptococcus spp., viral nervous necrosis virus (VNNV) were dominant in MP group.

• Journal of fish pathology
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• v.19 no.3
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• pp.207-214
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• 2006

Diagnostic monitoring in fish farms with land-based tanks and net cases was conducted in eastern, western, southern and Jeju island of Korea for the summer period from 2000 to 2006. Total 3,518-fish samples of marine and freshwater fishes in 25 fish species were tested for pathogens. Fish species tested were olive flounder (Paralichthys olivaceus), fleshy prawn (Fenneropenaeus chinensis Osbeck), black rockfish (Sebastes schlegeli), rock bream (Oplegnathus fasciatus), red sea bream (Pagrus major), black seabream (Acanthopagrus schlegeli), sea bass (Lateolabrax japinicus), gray mullet (Mugil cephalus), rainbow trout (Onchorhynchus mykiss) and others. The infection rates by bacterial pathogens in the years of 2000, 2001, 2002, 2003, 2004, 2005 and 2006 were 22.4%, 34.5%, 14.1%, 15.3%, 17.7%, 13.5% and 5%, respectively. The infection rates by parasitic pathogens were 20%, 33.8%, 12.4%, 14.1%, 9.2%, 10.5% and 10.7%, respectively. The infection rates by viral pathogens were 22.4%, 13.5%, 10.3%, 5.4%, 9.7%, 10.2% and 15.8%, respectively. The infection rates by mixed pathogens were 10.3%, 0%, 44.9%, 50.9%, 31.9%, 38.4% and 39.6%, respectively. The rates of mixed infections were very low until 2001. The rates were higher than those of singer infections from 2002 to 2006. During the diagnostic monitoring from 2000 to 2006, the main bacterial pathogens were Vibrio (41.2%) and Streptococcus (28.8%). The infection rate by protozoa (85.7%) mainly including Scuticociliates and Trichodina was highest. The infection rate by viral necrosis virus (VNNV, 42.2%) was the highest of the viral pathogens.

• Journal of Life Science
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• v.25 no.11
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• pp.1280-1289
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• 2015

Fish-meat gel is being produced mostly relying on surimi and raw materials imported from Southeast Asia and North America and present in small amount in local markets. In this study, common farmed local fishes were examined as stable and reliable sources of surimi for fish-meat gel production. For testing, five main farmed-fish of Korea, namely; Bastard halibut (Paralichthys olivaceus), Red sea bream (Pagrus major), Korean rockfish (Sebastes schlegeli), Common mulle (Mugil cephalus), and Finespotted flounder (Pleuronichthys cornutus) were used following a traditional washing process. The quality of the surimi was determined by the values of water content, whiteness index, gel strength and impurity. Accordingly, fish-meat gel and surimi quality experiments were carried out by measuring compressive and texture properties, expressible moisture content, Hunter color scale values and SDS-page protein patterns. Also gel characteristics were compared with that of FA and RA grade surimi (Alaska Pollock). Fish-meat gels were prepared by salt mincing the farmed-fish surimi with NaCl (2% w/w) and moisture adjustment to 84% by ice water adding. Prepared fish-meat paste was filled into 20-25 cm long polyvinylidene chloride casings and heated at 90℃ for 20 min. The whiteness values of fish-meat gels produced from surimi were increased by using farmed-fish and became comparable to that of FA Alaska Pollock gel. Among all tested farmed-fish, P. olivaceus and P. major exhibited better properties than RA Alaska Pollock and similar properties to FA Alaska Pollock. Therefore, current data suggests that fish farming can be an efficient and sustainable fish-meat source for fish-meat gel production in Korea.

• Korean Journal of Environmental Biology
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• v.37 no.4
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• pp.474-482
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• 2019

Disease monitoring in wild aquatic animals is necessary to obtain information about disease occurrence, disease agents, and the transmission of diseases between wild and cultured species. In this study, we monitored viral diseases in wild marine fish and crustacea caught by trawl in Korea in April and October 2018. We monitored the viral diseases in 977 fish from 39 different species and 287 crustacea from 14 different species. In fish, we collected kidney and spleen to detect viral hemorrhagic septicemia virus (VHSV), red sea bream iridovirus (RSIV), marine birnavirus (MABV), hirame rhabdovirus (HRV), and lymphocystis disease virus (LCDV). In crustacea, we monitored white spot syndrome virus (WSSV), infectious hypodermal and hematopoietic necrosis virus (IHHNV), taura syndrome virus (TSV), infectious myonecrosis virus (IMNV), yellowhead disease virus (YHDV), and white tail disease virus (WTDV) using pleopods, pereiopods, gills, muscle, and hepatopancreases. Although none of the viral diseases tested in this study were detected in the samples, these results will help disease control between aquaculture species and wild aquatic animals.

• Journal of fish pathology
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• v.13 no.2
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• pp.121-127
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• 2000

From August to October 1998, over 60% mortality of cultured striped beakperch Oplegnathus fasciatus was occurred in net cages along the southern coast of Korea. Moribund fish showed some clinical signs of lethargic behavior, dark coloration or decoloration, severe gill anemia and enlargement of spleen. Also enlarged basophilic cells showing Feulgen -positive reaction were observed in the tissue section of spleen, kidney, liver and heart of the diseased fish. GF cells inoculated with spleen homogenate of diseased fish produced cytopathic effect of enlarged and rounded cells, therefore the causative virus was isolated from diseased fish. Striped beakperch fingerlings intraperitoneally inoculated with the causative virus ($10^4TCID_{50}$/0.1 ml) revealed symptoms similar to those of naturally infected fish and died from 7 to 14 days post injection. Transmission electron microscopy revealed that the causative virus was enveloped icosahedral particle with 120~130 nm in diameter. PCR products of the expected size (500 bp) were amplified with a primer set based on the ATPase gene of RSIV(red sea bream iridovirus) using template DNAs which were extracted from the spleen of diseased fish and GF cells inoculated with the causative virus. According to the analysis of nucleotide sequence of these PCR products, the sequence from ATPase cDNA gene of the causative virus showed 95% homology with that of RSIV. These results indicate that the mass mortality in the cultured striped beakperch was caused by the infection of iridovirus similar to RSIV.

• Journal of fish pathology
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• v.23 no.2
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• pp.155-163
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• 2010

The epidemiological study was performed to survey the prevalence of fish pathogens in cultured olive flounder, Paralichthys olivaceus from 2005 to 2007. In this study, the fish pathogens were detected from 1,528 among 2,238 fish samples collected yearly in 5 sites from February, May, August and November. Annual incidences for three years show a yearly increase and there were 60.6% in 2005, 66.7% in 2006 and 72.3% in 2007, respectively. Seasonal prevalence was 63.5% in February, 67.4% in May, 75.1% in August and 64.4% in November for three years. The detection rates of 6 viral pathogens were 35.6% in 2005, 44.6% in 2006 and 24.4% in 2007 and the peak rate was 55.4% at adult size group (above 41cm). Viral nervous necrosis virus (24.7%) has been the most predominant virus in this investigation, while much lower rates were noted in viral haemorrhagic septicemia virus (10.6%) and red sea bream iridovirus (0.9%).