• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.6
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• pp.435-439
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• 2008

The antimicrobial resistance of 160 strains of Enterococcus faecalis and 173 strains of E. faecium to 12 antimicrobial agents was investigated. The test strains were isolated from 126 wild seawater and farmed fish, including olive flounder (Paralichthys olivaceus), black rock fish (Sebastes schlegeli), red sea bream (Pagrus major), and sea bass (Lateolabrax japonicus), in 2005 and 2006. Overall, 91.9% of the E. faecalis isolates and 88.4% of the E. faecium isolates showed antimicrobial resistance to at least one antimicrobial agent. The pattern of antimicrobial resistance of the isolates differed little according to the species of fish. The percentage of E. faecalis and E. faecium with specific antimicrobial resistance differed according to the sample source. For the isolates from farmed fish samples, 66.7% of E. faecalis were tetracycline resistant and 54.5% of E. faecium were erythromycin resistant. By contrast, in the wild fish seawater samples, 92.0% of E. faecalis were rifampin resistant and 88.5% of E. faecium were tetracycline resistant.

• Fisheries and Aquatic Sciences
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• v.18 no.2
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• pp.203-209
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• 2015

Low-value fish is the most commonly used feed in Asian fish farms despite the fact that its application is controversial in regard to the sustainability and biosecurity of aquaculture. In this study, the causal agent of a disease outbreak at a Korean rockfish Sebastes schlegeli farm was investigated to determine whether the low-value fish used at the farm was the source. Infected Korean rockfish and Pacific sand eel used as feed were sampled from the farm, and bacterial cultures recovered from the internal organs of all sampled rockfish were isolated as pure cultures and later identified as Vibrio harveyi. The causal agent of the disease was also isolated from the kidneys of some of the sampled Pacific sand eels. This study provides additional evidence that the low-value fish used as feed at fish farms can be a key source of infectious diseases.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.4
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• pp.341-346
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• 2014

Transmissible spongiform encephalopathies (TSEs), also termed prion diseases, are a threat to food safety and to human and animal health. Variant Creutzfeldt-Jakob disease (vCJD) in humans is caused by the consumption of meat contaminated with bovine spongiform encephalopathy (BSE, mad cow disease). The BSE epidemic in the United Kingdom was shown to be related with the extensive use of BSE-contaminated meat-and-bone meal (MBM) and bovine offal. Many countries worldwide use MBM, as well as meat from cows, for aquaculture feed. This raises concerns about the safety of farmed fish, a major protein source for humans. The present work reviews recent studies on fish prion protein and the transmissibility of mammalian prion agents to fish, providing insights into the future direction of fish prion research.

• Proceedings of the Korean Aquaculture Society Conference
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• 2005.05a
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• pp.93-93
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• 2005

• Korean Journal of Ichthyology
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• v.20 no.4
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• pp.248-254
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• 2008

Olive flounder (Paralichthys olivaceus) is one of the most popular farmed fish in Korea. Genetic variability of the fish was investigated by means of microsatellite DNA markers. All of the 8 microsatellite loci were analyzed in this study. For the confirmation of genetic variation during a shift in generation, microsatellite variability was compared within the same hatchery strains but produced in different spawning years. When genetic variability of farmed flounders produced in 2006 and 2007 was compared with that of 2003, a marked reduction of genetic variability was observed in the 2006 and 2007 populations. Mean number of alleles per locus and expected mean heterozygosity decreased from 9.75 and 0.796 (in 2003 population) to 7.78 and 0.785 (in 2006 population), respectively. Moreover, we have observed the distortion of allele frequency. These results show that reduced genetic variability of farmed olive flounder in processed generation has lower numbers of alleles and genetic variability than these of wild fish. Our results suggest that to have a sustainable aquaculture of this species, there is need for scientific broodstock management based on genetic variation and more intensive breeding practices to improve genetic diversity and to avoid detrimental inbreeding effects.

• The Journal of Fisheries Business Administration
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• v.37 no.3 s.72
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• pp.1-24
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• 2006

In terms of the size of aquaculture farms and production volume, inland freshwater aquaculture is much smaller than marine aquaculture in Korea. However, freshwater aquaculture provides fish which is not produced in the sea. Freshwater aquaculture plays an important role in the efficient use of resources, development of local areas and economy vitalization in under - developed areas. freshwater aquaculture also helps ecosystem recovery by stocking farmed fry. As addressed above, inland freshwater aquaculture plays various roles and can not be ignored. However, freshwater aquaculture has been off the interest of fisheries authority. Considering a series of changes in the circumstances such as the government's disapproval of pen - raised aquaculture, higher standard for discharged water from aquaculture farms and a rapid increase in import of low price fish from other countries, it is difficult to expect the quantitative expansion of the freshwater aquaculture any more. Furthermore, freshwater aquaculture lost the trust of people because of the use of Malachite green, and the consumption of farmed product plummeted last year. Even though it would be difficult to expect the quantitative expansion, we could expect qualitative growth and let the inland freshwater aquaculture keep playing the own roles. In order to achieve competitive advantage and regain the trust by providing safer farmed product, the government's support and freshwater aquaculture industry's active and voluntary efforts are very important. This paper suggests several points for the future oriented inland freshwater aquaculture in Korea such as strategic intensive development of selected species, the technical improvement and its diffusion, increased cooperation among the government authority, industry and scientists.

• Fisheries and Aquatic Sciences
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• v.26 no.10
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• pp.605-616
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• 2023

Scuticociliatosis, caused by the parasitic pathogen Miamiensis avidus, poses a significant threat to olive flounder farms in South Korea. Infected fish suffer from severe systemic infections affecting various organs, with potential secondary bacterial diseases. This study investigated the emergence of different M. avidus serotypes in 20 olive flounder farms on Jeju island, South Korea, from 2015 to 2020. Additionally, we identified Tenacibaculum maritimum as a co-infecting bacteria. Based on serotyping and monitoring data, we developed a trivalent vaccine targeting two serotypes of M. avidus and one strain of T. maritimum. The efficacy of the vaccine was evaluated under laboratory conditions and demonstrated a relative percentage of survival (RPS) of 75%, 80%, and 93% for M. avidus serotype I, M. avidus serotype II and T. maritimum, respectively. Furthermore, successful field trials conducted on four different olive flounder farms resulted in significantly higher survival rates (52%-76% RPS) and weight gains in vaccinated fish. Overall, this study presents an effective vaccine against M. avidus and T. maritimum infections in farmed olive flounder, making a valuable contribution to sustainable aquaculture in South Korea.

• Journal of fish pathology
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• v.36 no.2
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• pp.415-422
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• 2023

In veterinary medicine for mammals, studies are being conducted to confirm the effects of antioxidants using pathological toxicity model studies, and are also used to confirm the effect of mitigating liver or kidney toxicity of specific substances. It was considered necessary to study such a toxicity model for domestic farmed fish, so thioacetamide (TAA), a toxic substance that causes tissue damage by mitochondrial dysfunction, was injected into rainbow trout (Oncorhynchus mykiss), a major farmed freshwater fish species in Korea. The experiment was conducted with 40 rainbow trout (Oncorhynchus mykiss) weighting 53 ± 0.6 g divided into two groups. Thioacetamide(TAA) 300mg/kg of body weight was intraperitoneally injected into rainbow trout and samples were taken 1, 3, 5, 7 days after peritoneal injection. As a result, in serum biochemical analysis, AST levels related to liver function decreased 3 and 5 days after intraperitoneal injection and increased after 7 days, and ALT levels also increased after 7 days. In addition, creatinine related to renal malfunction increased 3 and 5 days after TAA injection. In histopathological analysis, pericholangitis and local lymphocyte infiltration were observed in the liver from 1 day after intraperitoneal injection of TAA, and hepatic parenchymal cell necrosis was also observed from 3 days after intraperitoneal injection. Hyaline droplet in renal tubular epithelial cell was observed from 1 day after TAA injection, and acute tubular damage such as tubular epithelial cell necrosis appeared from 3 days after TAA injection. Accordingly, it is thought that it will be able to contribute to studies that require a toxicity model.

• The Journal of Fisheries Business Administration
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• v.51 no.4
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• pp.69-83
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• 2020

The purpose of this paper is to empirically investigate whether asymmetric price transmission exists in the distribution stage of farmed olive flounder market. For the analysis, time series data were used for the producer prices of Jeju and Wando, and the wholesale prices of Incheon, Hanam and Busan. Through the Granger causality test, the causal relationship from the producer price to the wholesale price was derived and the asymmetric price transmission was analyzed using the autoregressive distributed lag model (ARDL). As a result of the analysis, it was found that there is a phenomenon of 'positive asymmetric price transmission' from the producer price to the wholesale price. This result can be one evidence that excess profits are received in the intermediate distribution stage, and can be said to be a result showing the incompleteness and inefficiency of the distribution structure of the farmed olive flounder. In the future, it is required to establish an information-sharing system in all stages of production, distribution, and consumption that can create a competitive environment for distribution participants and resolve information asymmetry. Also, it is necessary to review the distribution center specializing in live fish from the viewpoint of the establishment of new distribution channels and sales diversification strategy under the rapidly changing fisheries environment.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.2
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• pp.158-167
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• 2015

A lateral flow immunoassay kit based on antigen-antibody interactions was developed to detect residues of beta-lactams, quinolones, tetracyclines, and sulfonamides in farmed fish. Group-specific antibodies showing cross-reactivity with other antibiotics in the same group were produced in rabbits. The rabbits were immunized eight times to obtain the maximum titers. Antibodies were extracted from the antisera collected from the immunized rabbits and produced group-specific reactions with antibiotics from the four groups. A kit was prepared that optimize conditions for the antigen-antibody reaction, using colloidal gold conjugated antibodies, and was designed to detect the four groups of antibiotics simultaneously. The kit enabled the detection of antibiotics in the four groups at below maximum residue limits (MRLs), which were $200{\mu}g/kg$ for tetracyclines, $100{\mu}g/kg$ for sulfonamides, $50{\mu}g/kg$ for beta-lactams, and $100{\mu}g/kg$ for quinolones. The cross-reactivity of the antibodies ranged from 10-80% for the sulfonamides, 20-100% for tetracyclines, 38-100% for quinolones, and 20-100% for the beta-lactams, confirming that the antibodies were group specific. The test kit was used 30 times to examine spiked antibiotics at the limits of detection (LODs) and all produced positive results, indicating high sensitivity. The LODs for the assay ranged from 4-20 ng/mL for beta-lactams, 25-50 ng/mL for sulfonamides, 20-100 ng/mL for tetracyclines, and 30-80 ng/mL for quinolones, and there were no false negative reactions at above these LODs. In addition, all of the LODs of the developed kit were correlated with high-performance liquid chromatography (HPLC) data. Our lateral flow immunoassay kit can simultaneously detect antibiotic residues from a large number of fish samples rapidly, strengthening the safety of domestic farmed and imported fish.