• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.4
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• pp.506-514
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• 2020

We investigated seed management and feeding regime of larval red spotted grouper Epinephelus akaara using live food organisms. Fertilized eggs were produced in March 2020 by manipulating photoperiod and water temperature. Broodstock (F0) produced approximately 0.30×10⁶ eggs, of which 0.25×10⁶ were fertilized; first-generation broodstock (F1) produced 2.00×10⁶ eggs, of which 1.90×10⁶ were fertilized. Larvae were reared at temperatures of 21.0-24.5℃. The feeding regime consisted of rotifers Artemia, and commercial pellet feed. From 5-8 days after hatching (dah), rotifers collected from high-density incubation tanks were fed to grouper larvae at a density of 10-20 individuals/mL. From 9-30 dah, rotifers collected from low-density incubation tanks were fed to larvae at a density of 10-20 individuals/mL. Newly hatched Artemia were provided from 20-24 dah and enriched Artemia from 25-50 dah. Commercial pellet feed was given starting at 13 dah. The average mouth size in hatchlings was 263.4±3.7 ㎛ at 5 dah, 406.7±21.0 ㎛ at 11 dah, and 856.9±136.6 ㎛ at 21 dah. At 1 dah, larvae had a mean total length of 1.95±0.06 mm. At 66 dah, the mean TL was 4.0 cm. The final number of surviving red spotted grouper larvae was 218,380 fishes.

• Journal of Marine Life Science
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• v.3 no.1
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• pp.22-30
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• 2018

In this study, pilot study on the introduction of stationary fishery was performed to solve the problem of fisheries resource reduction. The Fyke net, which is a test fishing net was selected considering the environment, operation and management costs of Ulleungdo, conditions that can be operated by small fishing vessels and personnel. As a result of 11 times survey using Fyke net from April to May 2017, 2,735 individuals and 983.4 kg caught and the dominant species were red seabream, yellowtail, olive flounder, mitra squid, horse mackerel, filefish, etc. In conclusion, if the production of squid, which is one of the major fisheries resources of Ulleungdo, is continuously decreased, it is considered that introduction of small-scale stationary fishery such as Fyke net would be useful as a means replace income of fishermen.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.2
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• pp.96-104
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• 2000

By using the offshore type submersible platform, Artificial sea floor anchored at a depth of forty meters several experimental studies have been conducted successfully during 1996. The facility consists of an artificial sea floor that floats at 7 meters below the surface, a machinery hut that projects above the surface at the center of the structure and a balance weight beneath the structure. The facility can be surfaced easily by using a water discharging pump in the water tank which is located at the center of it. To find out the behavioral character and the gathering factor of fishes around the artificial sea floor, investigations were carried out during the daytime and nighttime by direct observation and by echo-sounder. Around the testing reefs and artificial sea floor, six kinds of fishes were found by diving observation and the dominants were Scomber japonicus, Sebastes thompsoni and Oplegnathus fascitus. As Scomber japonicus was distributed around the artificial sea floor in dense small school, they were not seen elsewhere in the survey area. The artificial sea floor was concluded to act as a schooling ground far Scomber japonicus, Sebastes thompsoni and Oplegnathus fascitus. were close to the testing reefs(within 10m) in the daytime, and were thought to settle on the testing reefs at nighttime, To examine the distribution of 7shes around the artificial sea floor, an acoustic survey over a 1$\times$1km area, 0-50m in depth during the all day. Around the artificial sea floor many thin scattering fish echo(TS-54.5~ -51.5dB) and dense fish echo(TS-41~-38dB) were mainly distributed. Many scattering fish echoes, which were thought to be a mixture of small squid, pelegic crustacea and ethers, were distributed over the whole survey area. A dense fish school stayed beneath the artificial sea floor for a short duration. These phenomena were concluded to show an attraction and detention function of the artificial sea floor.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.4
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• pp.426-433
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• 2021

This study aimed to determine the appropriate salinity condition for optimal cultivation of the juvenile hybrid grouper Epinephleus akaara♀×E. lanceolatus♂ in conditions of decreasing salinity. The survival, growth, metabolic rate, stress, and histological response were investigated in juvenile hybrid grouper exposed to different salinities for 30 days. At 0 psu, the survival rate of the juvenile hybrid grouper was 60% on the 2nd day of exposure and all individuals died on the 3rd day of exposure. At salinities above 3 psu, all animals survived throughout the exposure period. Growth rate for body weight of the juvenile hybrid grouper was the highest in the control and the lowest at 10 psu. Plasma osmolality of the juvenile hybrid grouper exposed to different salinities was 313-355 mg Osmol/kg at salinities above 10 psu, and then decreased to 225-264 mg Osmol/kg at salinities below 5 psu. The oxygen consumption rate tended to decrease as the salinity decreased. Stress responses of the juvenile hybrid grouper were analyzed with decreasing salinity. Therefore, it is considered that a salinity of more than 20 psu is suitable for the culture of the juvenile hybrid grouper.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.6
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• pp.850-860
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• 2023

The effects of dietary mannan oligosaccharides, Lactobacillus plantarum, Bacillus subtilis, and Bacillus licheniformis supplementation on hybrid grouper Epinephelus akaara ♀×Epinephelus lanceolatus ♂ were evaluated. The fish were fed a basal diet and five other diets consisting of 0.6% mannan oligosaccharides, L. plantarum, B. subtilis, and B. licheniformis and mixture of each 0.15% prebiotic and all the probiotics (designated as MOS, LP, BS, BL, and SYN) for 56 days. Growth performance and feed utilization showed no significant differences among all experimental groups. Lipid level of whole-body was significantly high in MOS and BL groups. Plasma aspartate aminotransferase was significantly low in BL and SYN groups. Nitro-blue tetrazolium, lysozyme and anti-protease, and glutathione peroxidase in BS, SYN, and all probiotic groups, respectively, were significantly high. Intestinal Vibrio bacteria was significantly low in all probiotic and SYN groups. Gene expression of interleukin-1β and interleukin-10 in SYN group; transforming growth factor β2 in MOS and BS groups, toll-like receptor 2-2 in BS and BL groups; and C-type lectin in MOS, LP and SYN groups were significantly upregulated. Our findings indicate that mannan oligosaccharides, L. plantarum, B. subtilis, and B. licheniformis could improve innate immunity, antioxidant capacity, anti-inflammation, and intestinal microbiota of hybrid grouper.

• Korean Journal of Ichthyology
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• v.13 no.2
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• pp.143-157
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• 2001

To determine seasonal fluctuations in abundance and species composition of the fishes, samples were collected by bottom trawl off Kohung Penisula from February to December 1999. A total of 7,197 fishes were sampled and identified into 123 species, 54 families, 13 orders and 2 classes. Of the 13 orders, Perciformes, Scorpaniformes, Pleuronectiformes and Tetraodontiformes accounted for approximately 82.9% of the total. Gobiid fishes were dominant, representing 13 species. Leiognathus nuchalis, Konosirus punctatus, Engraulis japonicus, Ilisha elongata, Trichiurus japonicus, Argyrosomus argentatus, Ditrema temmincki, Takifugu niphobles, Hexagrammos otakii and Lateolabrax japonicus accounted for 71.4% of the number of individuals. Mugil cephalus, Sebastes schlegeli, Lateolabrax japonicus, Konosirus punctatus, Hexagrammos otakii, Conger myriaster, Liparis tanakai, Seriola quinqueradiata, Trichiurus japonicus, Sebastiscus marmoratus and Limanda yokohamae accounted for 50.7% of the total biomass. The number of species showed a seasonal variation, higher in spring, summer and autumn than in winter. The Largest numbers of individuals and greater biomass were observed in August. The economic fishes of this area were Konosirus punctatus, Engraulis japonicus, Mugil cephalus, Sebastes inermis, Sebastes schlegeli, Sebastes oblongus, Sebastiscus marmoratus, Platycephalus indicus, Hexagrammos agrammus, Hexagrammos otakii, Lateolabrax japonicus, Epinephelus akaara, Epinephelus septemfasciatus, Seriola quinqueradiata, Pagrus major, Acanthopagrus schlegeli, Argyrosomus argentatus, Oplegnathus fasciatus, Trichiurus japonicus, Pampus echinogaster, Paralichthys olivaceus, Kareius bicoloratus, Limanda yokohamae and Takifugu porphyreus.