• Journal of fish pathology
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• v.32 no.1
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• pp.37-43
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• 2019

Due to the rapid global expansion of aquaculture industry during the past decades, production volume of aquatic organisms has accordingly grown. This has been accompanied by a rise in the incidence of diseases in aquatic organisms, leading to an increased use of aquatic medicines. While aquatic medicines are essential for the prevention and treatment of diseases of aquatic organisms, misuse can cause evolution of antibiotic-resistant bacteria and pose serious problems to the safety and hygiene of fisheries products. In this study, we surveyed and compared, by analyzing data compiled by all national control centers for aquatic animal diseases in South Korea, to estimate the amount of aquatic medicines sold in different regions between 2012 through 2015. Since we also examined the marketing routes of aquatic medicines, this basic data can be utilized for policy implementation to improve drug safety. In the future research, however, it will be clearly necessary to estimate directly the amounts of drugs actually applied to aquaculture organisms. The current sales figure data should be helpful for preparation of an effective system for aquatic drug use management.

• Fisheries and Aquatic Sciences
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• v.16 no.2
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• pp.93-99
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• 2013

In 2009, a systemic megalocytivirus infection associated with high mortality was detected for the first time in cultured starry flounder Platichthys stellatus in Korea. Diseased starry flounder had pale bodies and gill coloring and enlarged spleens. Histopathological examinations revealed basophilic enlarged cells in various organs of diseased starry flounder. Polymerase chain reaction (PCR) was performed on tissue samples using three published primer sets developed for the red sea bream iridovirus. PCR products were detected for all primer sets, except 1-F/1-R, which are registered by the World Organization for Animal Health (OIE). The part of the gene corresponding to the full open reading frame encoding the viral major capsid protein (MCP) was amplified by PCR. PCR products of approximately 1,581 bp were cloned, and the nucleotide sequences were analyzed phylogenetically. The MCP gene of the starry flounder iridovirus, designated SFIV0909, was identical to that of the turbot reddish body iridovirus (AB166788).

• Fisheries and Aquatic Sciences
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• v.19 no.6
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• pp.28.1-28.7
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• 2016

Background: Significant increases in the bacterial resistance to various antibiotics have been found in fish farms. Non-antibiotic therapies for infectious diseases in aquaculture are needed. In recent years, light-emitting diode technology has been applied to the inactivation of pathogens, especially those affecting humans. The purpose of this study was to assess the effect of blue light (wavelengths 405 and 465 nm) on seven major bacterial pathogens that affect fish and shellfish important in aquaculture. Results: We successfully demonstrate inactivation activity of a 405/465-nm LED on selected bacterial pathogens. Although some bacteria were not fully inactivated by the 465-nm light, the 405-nm light had a bactericidal effect against all seven pathogens, indicating that blue light can be effective without the addition of a photosensitizer. Photobacterium damselae, Vibrio anguillarum, and Edwardsiella tarda were the most susceptible to the 405-nm light (36.1, 41.2, and $68.4J\;cm^{-2}$, respectively, produced one log reduction in the bacterial populations), whereas Streptococcus parauberis was the least susceptible ($153.8J\;cm^{-2}$ per one log reduction). In general, optical density (OD) values indicated that higher bacterial densities were associated with lower inactivating efficacy, with the exception of P. damselae and Vibrio harveyi. In conclusion, growth of the bacterial fish and shellfish pathogens evaluated in this study was inactivated by exposure to either the 405- or 465-nm light. In addition, inactivation was dependent on exposure time. Conclusions: This study presents that blue LED has potentially alternative therapy for treating fish and shellfish bacterial pathogens. It has great advantages in aspect of eco-friendly treating methods differed from antimicrobial methods.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.5
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• pp.582-588
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• 2013

The impact of global warming on aquatic systems has been a priority research area in the past decade. However, the possibility that increased temperatures will cause shifts in viral disease outbreaks has not been well addressed. In the present study, with increasing water temperature (WT) in the coastal area of Korea, we estimated the possibility of changes in fish viral diseases. From the present time, WT may rise between 0.62 and $1.7^{\circ}C$ by 2050, and the effect on aquaculture could be more adverse than benefitial. Red seabream iridovirus disease (RSIVD) and viral nervous necrosis (VNN) cause high mortality above 22 and $24^{\circ}C$, respectively, and outbreaks could commence earlier and persist for prolonged periods. Nevertheless, the period of occurrence of viral hemorrhagic septicemia (VHS), which outbreaks at a lower WT (< $18^{\circ}C$), could be shorter than the current infectious period. Thermal stress in fish causes reductions in growth and immunocompetence; thus, increases in summer WT can lead to the development of new viral diseases. WT has a strong influence on fish population dynamics; therefore, entry of new viruses and changes in the prevalence of infection can be expected if carrier fishes are introduced or migrate to Korean waters.

• Journal of fish pathology
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• v.23 no.1
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• pp.99-106
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• 2010

Aquatic animal diseases control act which is to assure the prevention of outbreak and spread of aquatic animal diseases in Korea has come into effect since 22 December 2008. In order to prevent outbreak and spread of aquatic animal diseases, risk analysis is newly introduced. The introduction of risk analysis for movement of aquatic animals related to implementation of recommendation of the World Trade Organization (WTO) Agreement on the Application of Sanitary and Phytosanitary Measures and should be conducted in accordance with guidelines of OIE Aquatic Animal Health Code. This report involves gathering and analysing the information of international regulation and situations of risk analysis framework in Korea for movement of aquatic animals.

• Fisheries and Aquatic Sciences
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• v.14 no.2
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• pp.148-160
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• 2011

Thirty-one gross abnormalities that have been observed in tilapia are described: 10 fin, five eye, five jaw, four body shape, three head, two yolk sac, one operculum, and conjoined twins. Twenty-one have been described in published papers; the others were obtained from a survey. Breeding experiments revealed that three were heritable, while six were not heritable. Five could be caused by a bacterial infection, and one could be produced by a fungus. Four deformities were in offspring of males that had been injected with methyl methane sulphonate. Three were produced when sperm was treated with methyl methane sulphonate. Six were observed during sex reversal studies, and one was found following heat shock of fertilized eggs. Three were observed in polluted river water. The cause of other deformities is not known.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.4
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• pp.403-410
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• 2015

Viral nervous necrosis (VNN) is a serious disease of sevenband grouper Epinephelus septemfasciatus in Korean aquaculture farms. However, we suggest the following preventative methods for hatcheries: 1) disinfecting rearing water, 2) selecting spawners via ELISA and PCR, 3) selecting eggs via PCR, 4) disinfecting fertilized eggs, and 5) proper facilities management. When these methods are implemented, nervous necrosis virus (NNV)-free fish are produced because vertical and horizontal transmission is prevented. However, horizontal transmission of NNV through rearing seawater sourced from the environment during grow-out stages in sea cages can still occur. Live NNV vaccines with a low rearing temperature or Poly(I:C) immunization are very effective at preventing horizontal transmission of NNV in rearing farms. Furthermore, even after VNN is contracted, fish mortality can be reduced by administering Poly(I:C).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.3
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• pp.248-253
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• 2018

Freshwater farms are primarily located adjacent to rivers and lakes, facilitating the introduction and spread of pathogens into natural systems. Therefore, it is necessary to continuously monitor natural aquatic organisms, the breeding environment, and infection rates by pathogenic organisms. Fish and crustaceans were sampled 4 times in the Geum River estuary in 2016. The samples were analyzed for the presence of pathogens for reportable communicable diseases, including KHVD (koi herpesvirus disease), SVC (spring viraemia of carp), EUS (epizootic ulcerative syndrome) and WSD (white spot disease); parasite abundance was also examined. The dominant fish species were deep body bitterling Acanthorhodes macropterus (21.4%), followed by skygager Erythroculter erythropterus (12.7%). For crustaceans, Palaemon paucidens and Chinese mitten crab Eriocheir sinensis were dominant. Sixty fish and 36 crustacean species were examined for reportable communicable diseases. When using a specific primer set for each disease, PCR analysis did not detect any reportable communicable diseases in the samples. Some instances of Dactylogyrus, copepods, nematodes and metacercaria were detected. However, the PCR results indicated that the metacercaria were not Clonorchis sinensis.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.1
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• pp.47-53
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• 2018

The presence of pathogens in wild fish is a potential threat to the fish being raised nearby fish farm. Surveillance of these pathogens in the wild is, thus, highly important to keep fish in the farm safe from serious communicable diseases. Fish and crustacean were sampled 4 times at Soyang Lake in 2016. Pathogens for five reportable communicable diseases including KHVD (koi herpesvirus disease), SVC (spring viraemia of carp), EUS (epizootic ulcerative syndrome) and WSD (white spot disease), and parasites were investigated. In Soyang Lake, pale chub Zacco platypus was the most abundant. Forty seven pale chub, 8 Korea piscivorous chub Opsarichthys uncirostris, 3 oily shiner Sarcocheilichthys variegatus wakiyae and 2 crucian carp Cyprinus carassius were investigated for detection of target diseases of fish. Seventeen Caridina denticulata denticulata, 12 Oriental river prawn Macrobrachium nipponense and 1 Chinese mitten crab Eriocheir sinensis were used for detection of WSD. As the result, reportable communicable diseases were not detected in all the freshwater animals. Dactylogyrus was detected in Korea piscivorous chub. Copepoda was also detected in pale chub and Korea piscivorous chub. Metacercaria was detected in the pale chub sampled in September and October. Those were not metacercaria of liver fluke Clonorchis sinensis.

• Journal of fish pathology
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• v.32 no.1
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• pp.29-35
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• 2019

A monitoring was performed to survey the mortalities that had occurred in the aquaculture farms of olive flounder (Paralichthys olivaceus) in South Korea from 2015 to 2017. The indirect inquiry for entire farms and the sample survey for selected farms were carried out. The aquatic organism disease inspectors, who have a national license for the diagnosis and prevention of aquatic organism diseases and a have close relationship with the farms, investigated the rates and causes of mortalities according to the standard manual. The mortality rate by sample survey of farms in 2015, 2016, and 2017 were 24.78% (Chunnam: 17.86%, Jeju: 28.69), 30.19% (Chunnam: 24.45%, Jeju: 32.65), and 21.59% (Chunnam: 10.57%, Jeju: 26.00%), respectively. The major cause of mortality was scuticociliatosis, and the mortality caused by viral hemorrhagic septicemia and emaciation disease (Jeju) were also high. Our results can contribute to effective establishment prevention of epidemics system and acquired status as a disease-cleansing country.