• Fisheries and Aquatic Sciences
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• v.26 no.3
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• pp.234-240
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• 2023

Enteromyxum leei has been identified as the causative agent of emaciation disease in a wide range of marine fish hosts. In this study, we aimed to determine the effect of the parasitic infection of Enteromyxum species on starry flounder that were cultured in aquaculture farms of Jeju island in Korea. As the mortality of cultured olive flounder Paralichthys olivaceus because of E. leei infection increased, some fish farms on Jeju island attempted to culture the starry flounder Platichthys stellatus, as an alternative. Myxosporeans with a developmental stage similar to E. leei were found in the intestines of cultured starry flounders. The partial 18S rDNA of myxosporeans showed 100% similarity with E. leei. To reveal the effect of E. leei infection on starry flounder, the intensity of E. leei infection measured using quantitative polymerase chain reaction, and the condition factor (CF) of fish were measured and analyzed statistically. The results showed that high-intensity E. leei infection significantly decreased the CF of the starry flounder. However, the pathogenicity of E. leei to starry flounder is low, considering its mortality and clinical signs.

• Journal of fish pathology
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• v.35 no.2
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• pp.247-250
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• 2022

About 6.7% mortality was reported in a starry flounder (Platichthys stellatus) aquaculture farm in 2022. Most of the diseased fish showed a loss of pectoral fin, hemorrhages on muscle and gills, pale gills, enlarged spleen, and nodules on kidney. Parasites, fungi or viruses (viral hemorrhagic septicemia virus and hirame novirhabdovirus) were not detected from diseased fish. However, numerous bacteria were isolated from liver, spleen and kidney. Nucleotide sequences of the A-protein-encoding virulence array protein gene (vapA) of the bacteria showed 99.93% identity with Aeromonas salmonicida subsp. masoucida. This study is the first report of isolation of atypical A. salmonicida in cultured starry flounder in Korea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.3
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• pp.298-301
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• 2019

We investigated the development of allotriploid embryos derived from a cross between female starry flounder Platichthys stellatus and male stone flounder Kareius bicoloratus. The second cleavage, mid-blastula, gastrula, and Kupffer's vesicle appearance stages, and hatching of embryos began 3.7, 25.6, 45.7, 87.7, and 213.2 h after cold shock at $6^{\circ}C$, respectively. The hatching and development time of triploid interspecific hybrid eggs was approximately the same as those of diploid starry flounder eggs at the same incubation temperature.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.4
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• pp.583-594
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• 2014

This study was performed to estimate biomass and provide management guidance through population ecological characteristics, including growth parameters, instantaneous coefficients of natural and fishing mortalities, and age at first capture of the starry flounder, Platichthys stellatus and olive flounder, Paralichthys olivaceus of Korea. For describing growth of this species, a von Bertalanffy growth model was adopted. The von Bertalanffy growth parameters estimated from a non-linear regression for starry flounder were $L_{{\infty}}=48.25cm$, K=0.16/yr, and $t_0=-1.48$, respectively and those for olive flounder were $L_{{\infty}}=86.46cm$, K=0.26/yr, and $t_0=-0.29$, respectively. Biomass of Platichthys stellatus was estimated by direct biomass estimation method was 2.6 M/T, that was estimated by indirect method was 13.4 M/Tt. Those of Paralichthys olivaceus were estimated as 10.1 M/T, 19.3 M/T, respectively. An yield per recruit analysis showed that the current yield per recruit on Platichthys stellatus was about 48.2 g with F=0.646/yr and the age at first capture ($t_c$) 1.35yr, that on Paralichthys olivaceus was about 167.6 g with F=1.121/yr and the age at first capture ($t_c$) 1yr.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.6
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• pp.903-909
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• 2022

Triploid fish have attracted the attention of fish farmers owing to of their larger cell size compared to that of diploid fish and their ability to utilize the energy required for sexual maturation for growth instead. However, the effect of increased growth in triploid fish has shown varying results. Therefore, this study aimed to compare growth between diploid and triploid starry flounders and diploid and triploid hybrid juveniles (starry flounder, Platichthys stellatus ♀×stone flounder, Kareius bicoloratus ♂) based on breeding water temperature to investigate the effect of increased growth in triploid fishes. The experiment was performed by categorizing the water temperature as high temperature (EXP. 1, 14.5-23.5℃) and low temperature (EXP. 2, 6.4-13.3℃) based on the optimal water temperature for starry flounder breeding. In EXP. 1, the growth of starry flounder triploids and hybrid triploids was significantly higher than that of diploids. However, in EXP. 2 the weight gain and specific growth rate of the starry flounder triploid were higher, and the growth of starry flounder was higher than that of the hybrids.

• 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).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.1
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• pp.109-115
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• 2023

Interspecific hybridization is a beneficial strategy in aquaculture. In this study, diploid hybrids were produced through interspecies hybridization of flounder Platichthys bicoloratus ♀ × starry flounder P. stellatus ♂, which became commercial within a year. These hybrids exhibited an advantage in growth ability, with female hybrids growing twice as large as males at 11 months. Furthermore, hybrid flounders exhibited faster growth rates than starry flounders and reciprocal hybrids. The average growth rate of hybrids was 1.37 and 1.18 times greater than that of starry flounder and reciprocal hybrids at 5.5 months, respectively; Additionally, feed efficiency was 1.21 and 1.10 times higher than that of the experimental groups. The experiments were conducted at five temperatures to determine the optimal fry production method. Six weeks of culture resulted in a significant temperature effect, with maximum growth at 27℃. However, over 90% of the males occurred in the groups at temperatures above 24℃. Therefore, the optimum temperatures for survival, growth, condition factor and frequency of the best-sized fingerling at 13 weeks of age were estimated at 21℃. Thus, hybrid flounders are of great potential for use in the flounder aquaculture industry.

• Journal of Aquaculture
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• v.20 no.3
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• pp.173-177
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• 2007

An experiment was performed to obtain cryopreservation techniques of starry flounder (Platichthys stellatus) sperm. Milt obtained from 24 males were cryopreserved using two diluents, artificial seminal plasma (ASP) and Stein's solution (SS) with three cryoprotectants, dimethyl sulfoxide (DMSO), methanol, and glycerol concentrated from 5% to 20%. Post-thaw sperm activity (motility and/or speed) revealed the highest in 10% DMSO and 15% methanol in ASP and SS as diluent. Motility and speed of cryopreserved sperm were decreased according to increase of glycerol concentration. To conclude, DMSO was a better cryoprotectant than methanol or glycerol for cryopreservation of starry flounder sperm. Glycerol was incongruent cryoprotectant because of toxic to starry flounder sperm. Most cryopreserved spermatozoa without cryoprotectant showed the enlarged head with granulated chromatin and ruptured plasma membrane by freezing and thawing injuries compared with unfrozen normal spermatozoa.

• Journal of fish pathology
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• v.21 no.3
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• pp.209-217
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• 2008

A disease with mass mortality characterized exophthalmia and abdominal distension by ascites occurred in farmed starry flounder, Platichthys stellatus in Pohang since October of 2007. Severe necrosis and infiltration of inflammatory cells were observed in tissue histopathological sections from liver, kidney, spleen and heart of the diseased fish. The catalase-negative and gram positive cocci with -hemolysis were isolated from moribund fish. Analysis of the API profiles and the multiplex PCR of the isolates showed that strains were identified as Streptococcus parauberis. In API profiles, S. parauberis isolated from starry flounder differed from those of olive flounder, Paralichthys olivaceus to the test of arginine dihydrolase, D-mannitol, D-sorbitol and α-lactose. And the strains, PH0710 and PH0711, were strongly lethal for starry flounder (LD50 ranging from 4.2×103~4.2×102 cfu/fish at 7 days after intraperitoneally inoculation). This is the first report on a S. parauberis infection in starry flounder.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.5
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• pp.630-636
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• 2014

To investigate the characteristics of hybrid eggs and larva produced by olive flounder Paralichthys olivaceus females and starry flounder Platichthys stellatus males, we examined the developmental speed of hybrid eggs at different water temperatures. The developmental speed of hybrid eggs tended to increase with increasing water temperature. Specifically, the hatching times were 91 hrs, 62 hrs and 43 hrs at $10^{\circ}C$, $15^{\circ}C$ and $20^{\circ}C$, respectively. The mean biological minimum temperature of the hybrid was $1.3^{\circ}C$, which is in between that of the olive flounder and the starry flounder. In high water temperatureseasons, slower growth was observed in hybrids of the starry flounder which is a coldwater fish.