• Journal of fish pathology
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• v.36 no.2
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• pp.191-211
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• 2023

Rock bream iridovirus (RBIV) causes high mortality and economic losses in rock bream (Oplegnathus fasciatus) aquaculture industry in Korea. Although, the immune responses of rock bream under RBIV infection have been studied, there is not much information at the different stages of infection (initial, middle and recovery). Gene expression profiling of rock bream under different RBIV infection stages was investigated using a microarray approaches. In total, 5699 and 6557 genes were significantly up- or down-regulated over 2-fold, respectively, upon RBIV infection. These genes were grouped into categories such as innate immune responses, adaptive immune responses, complements, lectin, antibacterial molecule, stress responses, DNA/RNA binding, energy metabolism, transport and cell cycle. Interestingly, hemoglobins (α and β) appears to be important during pathogenesis; it is highly up-regulated at the initial stage and is gradually decreased when the pathogen most likely multiplying and fish begin to die at the middle or later stage. Expression levels were re-elevated at the recovery stage of infection. Among up-regulated genes, interferon-related genes were found to be responsive in most stages of RBIV infection. Moreover, X-linked inhibitor of apoptosis (XIAP)-associated factor 1 (XAF1) expression was high, whereas expression of apoptosis-relate genes were low. In addition, stress responses were highly induced in the virus infection. The cDNA microarray data were validated using quantative real-time PCR. Our results provide novel inslights into the broad immune responses triggered by RBIV at different infection stages.

• Fisheries and Aquatic Sciences
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• v.25 no.3
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• pp.151-157
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• 2022

Various approaches have been applied to transform aquaculture from a manual, labour-intensive industry to one dependent on automation technologies in the era of the fourth industrial revolution. Technologies associated with the monitoring of physical condition have successfully been applied in most aquafarm facilities; however, real-time biological monitoring systems that can observe fish condition and behaviour are still required. In this study, we used a video recorder placed on top of a fish tank to observe the swimming patterns of rock bream (Oplegnathus fasciatus), first one fish alone and then a group of five fish. Rock bream in the video samples were successfully identified using the you-only-look-once v3 algorithm, which is based on the Darknet-53 convolutional neural network. In addition to recordings of swimming behaviour under normal conditions, the swimming patterns of fish under abnormal conditions were recorded on adding an anaesthetic or lowering the salinity. The abnormal conditions led to changes in the velocity of movement (3.8 ± 0.6 cm/s) involving an initial rapid increase in speed (up to 16.5 ± 3.0 cm/s, upon 2-phenoxyethanol treatment) before the fish stopped moving, as well as changing from swimming upright to dying lying on their sides. Machine learning was applied to datasets consisting of normal or abnormal behaviour patterns, to evaluate the fish behaviour. The proposed algorithm showed a high accuracy (98.1%) in discriminating normal and abnormal rock bream behaviour. We conclude that artificial intelligence-based detection of abnormal behaviour can be applied to develop an automatic bio-management system for use in the aquaculture industry.

• Journal of fish pathology
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• v.29 no.1
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• pp.7-12
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• 2016

In a previous study on the parasites of cultured rock bream (Oplegnathus fasciatus), we reported the discovery of a new species, Ceratomyxa oplegnathus, obtained from the gallbladder. In the present study, we found another Ceratomyxa species, C. sparusaurati, also from the gallbladder of rock bream. The morphological and ultrastructural characteristics of C. sparusaurati were investigated using light and transmission electron microscopy (TEM).

• Journal of fish pathology
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• v.2 no.2
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• pp.71-74
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• 1989

Ichthyophonus disease had broken out among rock bream in Dec. 1989. Diseased-fish showed markedly stunted growth and darkish coloration, and anatomically the liver with small white nodules, tumefied spleen with its granulous surface, and the markedly tumefied kidney. Microscopic examination of liver, kidney, spleen and gill from 10 rock bream revealed cyst of the fungus Ichthyophonus sp. Rock bream were heavily infected with the highest concentrations of spherical multinucleate bodies in the liver, the spleen, the kidney and the gills. In heavily infected sectors of tissue a common necrotic zone was formed around spore aggregates. Spherical multinucleate hyphal terminal bodies developed thin hyphae longer than 1mm which divided into many branches.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.2
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• pp.78-84
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• 2006

A high performance liquid chromatography assay method for spiramycin in fish muscle was developed. The developed method was evaluated and validated by monitoring spiramycin in olive flounder (Paralichthys olivaceus), black rock fish (Sebastes schlegeli) and in live conger eel (Anguilla japonica) in fish farms and distribution centers. Using the developed method, the recovery rate was up to 82.4-88.8%, which was higher than that of conventional methods (77.6-87.1%). In particular, the proposed sample treatment protocol was suitable for use with fish samples to remove low molecular weight materials and pigments that could interfere an accurate analysis. The prepared stock solution was very stable, and it remained chemically stable for 5 weeks at $4^{\circ}C$. The performance limit of the developed method for spiramycin acid in fish muscle was 0.05 ppm. One hundred thirty-four fish samples including olive flounder, black rock fish and live conger eel were analyzed to evaluate the overall efficiency of the modified method and to monitor the actual condition of spiramycin usage in fish farms. Olive flounder and black rock fish were collected from fish farms in coastal areas of Korea, and live conger eels were purchased from a fish market in the Busan area from September 2001 to March 2002. According to the overall performance of the developed method, it was considered suitable for the monitoring of spiramycin in fish muscle. The suggested method of analysis for spiramycin in fish muscle is registered in the Korean Official Methods of Food Analysis and is currently tieing utilized for fishery products inspection by the Korea Food and Drug Administration and the National Fisheries Products Quality Inspection Service.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.2
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• pp.118-127
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• 2011

This study was investigated seasonal variation and species composition of fish species at artificial reefs (octangle three-stage compartment type and dice type)and natural rock in the Shinyang-Ri coastal waters off Jeju Island with visual census method in January 2009, April 2009, July 2009, September 2009, December 2009, March 2010, June 2010, and September 2010. A total of 44 fish species was occurred, and the dominant fish species were Apogon semilineatus, Chromis notata, Trachurus japonicus, Sebastes thompsoni and Apogon doederleini. The number of individuals of fishes was higher at April 2009 and March 2010, however, lower at June 2010 and September 2010. The number of fish speices was higher at artificial reefs than those of at natural rock. Apogon semilineatus was dominant at octangle three-stage compartment type and the dice type artificial reefs, whereas Chromis notata was for natural rock. These results indicated that artificial reefs were good habitats for a variety of fish species in the Shinyang-Ri coastal waters off Jeju Island.

• Development and Reproduction
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• v.19 no.2
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• pp.97-109
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• 2015

We assessed the effects of various dietary conditions on the growth, phenotypic traits, and morphometric dimensions of rock bream, Oplegnathus fasciatus and on the morphometric dimensions of sectioned olive flounder, Paralichthys olivaceus. Rock bream in the fed group increased in body weight, standard length, and condition factor, but these parameters decreased significantly for fish in the starved group (P < 0.05). The head connection dimensions of fish in the fed group decreased, while for starved fish there was increase in external morphometric dimensions (P < 0.05). In both species, sectioned morphometric analysis revealed that fish in the fed group had a larger body circumference and cross-cut sectional area, and greater cross-cut section height, relative to the starved group (P < 0.05).

• The Journal of Fisheries Business Administration
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• v.48 no.2
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• pp.53-66
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• 2017

More than 90% of cultured fish is consumed by sliced raw fish which is usually an eating out menu in South Korea. In order to develop the aquaculture industry in Korea, It is very important to know whether consumers can differentiate each species or not and how consumers recognize each species by certain criteria. for example taste, seasonal preference. The purpose of this study is to understand the competitive relationship through positioning studies of each species by the selection attributes. A total of 221 consumers were surveyed in korea. This study adapted multidimensional scaling(MDS) analysis to explore how consumers position sliced raw fish species based on selection attributes. This study has produced perceptual maps of sliced raw fish market. Empirical data was collected from sliced raw fish consumers in Korea. The results of MDS analysis reveal that 7 species are divided into 3 groups(flat fish, black rock fish), (red sea bream, salmon, tuna), (sea bass, gray mullet). In this study flat fish and black rock fish are perceived as safe, familiar, good value species. Red seabream, salmon, tuna are perceived as luxurious species. Sea bass and gray mullet are perceived as unfamiliar species.

• The Journal of Fisheries Business Administration
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• v.52 no.3
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• pp.27-38
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• 2021

This study is aimed to figure out the productivity and variability of cage-aquaculture changes. According to the analysis, the productivity of major fish species has been increasing, except mullet. Although the regional productivity has decreased in the last two years, it has been on the rise considering as a whole. Gyeongsangnam-do showed the highest level of productivity by region. Productivity by species was also higher than other regions in the cases of rock fish, mullet and sea bream followed by productivity of Chungcheongnam-do. The production of marine cage-culture in Jeollanam-do is the second largest in Korea in value/weight while its productivity is lower than that of Chungcheongnam-do. When it comes to comparison by region, Gyeongsangnam-do shows the lowest productivity variation. And Jeollanam-do shows the second-lowest variation in productivity that is only about half of that of Chungcheongnam-do province. Thus, it is found that Jeollanam-do region has an advantage in management stability while its productivity is low. On the other hand, productivity by species was also analyzed. Gyeongsangnam-do has the highest productivity by species for rock fish, mullet and sea bream whereas rock bream productivity is the highest in Jeollanam-do. Therefore, it probably needs to reflect these results when choosing regional-focused incubation fish species.

• Development and Reproduction
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• v.21 no.3
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• pp.249-257
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• 2017

In a 12-week experiment, the rock bream, Oplegnathus fasciatus, and olive flounder, Paralichthys olivaceus, were investigated to determine the effects of starvation on their physiological parameters. The protein and DNA contents of the starved fish were significantly higher than the initial values and those of the fed fish. The RNA contents and RNA/DNA ratios of the fed fish were significantly higher than those of the other groups (P<0.05). The hematocrit, hemoglobin, red blood cells (RBC), and mean corpuscular volume (MCV) of the fed rock bream were significantly higher than at baseline (P<0.05), whereas the mean corpuscular hemoglobin concentration (MCHC) of the fed fish was lower than at baseline (P<0.05). The hematocrit, hemoglobin, RBC, and MCHC of the starved group were significantly lower than the baseline values, whereas the MCV of the starved group was significantly higher than the baseline value (P<0.05). No significant difference in alanine aminotransferase was observed between the fed fish and baseline, whereas the starved fish value was significantly higher than the baseline value (P>0.05). There were no significant differences in cortisol levels. However, the glucose level in the fed group was significantly higher than the baseline level and that in the starved group was significantly lower than the baseline level (P<0.05).