• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.54 no.5
• /
• pp.660-667
• /
• 2021

In recent years, myxosporean infection from the cultured olive flounders Paralichthys olivaceus, have been frequently observed in Jeju island, South Korea. This study aimed to compare histopathological and molecular-biological methods of examining myxosporean infection from these flounders. Samples were obtained from affected individuals exhibiting emaciation or abdominal distention and a polymerase chain reaction (PCR) indicative of Parvicapsular anisocaudata, Enteromyxum leei and Kudoa septempunctata were initiated. Histopathological examination were conducted with H&E stained tissue sections, and then in-situ hybridization (ISH) reaction were processed with selected sections using P. anisocaudata, E. leei, K. septempunctata and Scuticociliate probes. Renal and intestinal tissue degeneration were common symptoms associated with all samples. Sever glomerular and renal tubular degeneration were evident, as were intestinal epithelial desquamation and spore formation in the epithelial cells. The results of conventional PCR analysis and ISH reactions revealed differences, and we suspect that various microparasites may have been associated with the symptoms manifested.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.50 no.1
• /
• pp.1-11
• /
• 2014

To compare the catches made using gillnets, trammel nets, and gillnets with supporting lines, several experiments were conducted with commercial vessels near Uljin and Pohang in Eastern Korea between July 2010 and May 2011. Two sets of 13 different nets were used, including 5 panels of gillnets and trammel nets each with stretched mesh sizes of 7.6, 9.1, 10.6, 12.1, and 13.6 cm and 3 panels of gillnets with a mesh size of 9.1 cm with supporting lines with different line spacing. The outer (stretched) mesh size of the trammel nets measured 51.5 cm. The target fishes of the fishing nets were various types of flounders. The catch rate of flounders was 50.7% of the total catch in weight. The total catch for all nets was 443.8 kg. The predominant species was pointhead flounder (Cleisthenes pinetorum). The total catch by trammel nets was 1.4 times that of the comparable gillnets. But more pointhead flounder were caught by gillnets than by trammel nets, though there was no significant difference. Fishermen catching the pointhead flounder in Korea said that there was no need to use trammel net to catch it; this was an unexpected finding compared to the findings of other flounder fisheries. The amounts of roughscale sole, brown sole, and blackfin flounder caught by trammel nets were greater than those caught by gillnets. The mean lengths (standard deviation) of blackfin flounder, pointhead flounder, brown sole, and roughscale sole were 21.0 (4.57), 22.9 (3.40), 24.7 (4.90), and 28.3 (5.43) cm, respectively; there were significant differences in mean length (p < 0.00001). Therefore, in order to catch flounder efficiently, the fishing nets and mesh size should be chosen according to the target species. One advantage of using supporting lines is that it prevents breakage by strengthening the material especially when utilized on a rough bottom. Catch by using gillnet with supporting lines was not greater than that by using trammel net for the conservation of fisheries resources.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.32 no.1
• /
• pp.37-41
• /
• 1999

This study was designed as a part of efforts to investigate the biochemical pollutant markers for diagnosis of marine pollutions by changes in cholinesterase activity of the flounder (Paralichthys olivaceus) in tie South Sea of Korea. Aceflcholinesterase (AChE) activities in brain and muscle of cultured flounders in the South Sea were significantly lower ($10\~20\%$ and $12\~19\%$, respectively) than those of wild flounder in Pohang of the East Sea as a control. Buthrylcholinesterase (BChE) activites in brain and muscle of cultured flounders in the South Sea were also remarkably lower ($25\~40\%$ and $22\~35\%$, respectively) than those of wild flounder in Pohang. Lactate dehydrogenase (LDH) activites in serum of cultured flounders in South Sea were significantly higher ($10\~55\%$) than those of wild flounder in Pohang. It suggests that AChE, BChE and LDH activities of the flounders clould be used as effective biochemical markers for early warning of environmental damages caused by organophosphorus pesticides.

• Fisheries and Aquatic Sciences
• /
• v.23 no.9
• /
• pp.26.1-26.9
• /
• 2020

Background: The study evaluated the effects of a butaphosphan and cyanocobalamin mixture on the immune system and stress in olive flounders, Paralichthys olivaceus. Methods: The mixture was intramuscularly injected into olive flounders at the current recommended dose. Furthermore, to determine the toxicity of overdose, a histological examination was performed after injection of 1-, 2-, and 4-fold higher than the recommended dose. Results: Immunity parameters were altered during the first 2 weeks after a single intramuscular injection of the mixture in olive flounders (average weight 20.5 ± 1.1 g). The levels of all tested items, except glutathione and antiprotease, were higher in the treated group than in the control group in the first week; the levels of all tested items were even higher in the second week in the treated group than in the control group. The level of nitro-blue tetrazolium, myeloperoxidase, and superoxide dismutase between the two groups differed significantly. Changes in the stress response to different seawater temperatures (increase or decrease in seawater temperature by 3-5 ℃ using 50 L heated or cooled seawater tanks) were studied by determining the changes in cortisol and glucose levels on days 1 and 7. Both cortisol and glucose levels were significantly lower in the treated group than in the control group. Histological analysis did not reveal any abnormalities after intramuscular injection of the mixture at doses that were 1-, 2-, and 4-fold higher than the recommended dose. Conclusions: Intramuscular injection of a butaphosphan and cyanocobalamin mixture is safe and effective in reducing stress and improving immunity in olive flounders.

• Journal of Marine Life Science
• /
• v.1 no.1
• /
• pp.56-62
• /
• 2016

In the present study, to clarify a possible relevance of blind-side hypermelanosis to chronic stress in cultured flounders, P. olivaceus, a serial experiment was tried with comparison of biochemical stress factors between wild type and hypermelanic type in cultured olive flounders. The mean size of experimental animal was total length 21.5±0.42 cm and body weight 87.5±6.1 g. The initial malpigmented area rate on the blind side skin was 0.63±0.12% and 16.7±4.7%, respectively, in the wild type and the hypermelanic type. The stress factors surveyed in the experiment were glucose (GLU), total protein (TP), cortisol, free type-thyroid hormones (FT₃ and FT₄) in plasma, and also moisture, crude protein, crude lipid, and crude ash in body muscle. As a result, GLU and TP were higher in hypermelanic type than in wild type. Plasma cortisol was also higher in hypermelanic type than in wild type. In FT₃ and FT₄, any difference between two groups was not observed. In body nutrient factors, the moisture and the crude ash in body composition were not different between two groups, but the crude protein was low and the crude lipid was high in the hypermelanic type. Therefore, it is concluded that the blind-side hypermelanosis of cultured flounders could be related with a chronic stress.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.39 no.4
• /
• pp.326-332
• /
• 2006

To investigate the effects of environmental salinity on the expression of the genes for growth hormone (GH) and prolactin (PRL) in the pituitary, and their receptors (GHR, PRLR) In the kidney, intestine, and gills in teleosts, we acclimated juvenile olive flounders (Paralichthys olivaceus) to different salinities (5, 15, 25, or 32 psu) for 3 days and examined their mRNA levels using the reverse transcription-polymerase chain reaction (RT-PCR). In the fish adapted to low salinity, the PRL mRNA levels in the pituitary were elevated dramatically, whereas the GH mRNA levels did not differ significantly. PRLR mRNA increased significantly in fish exposed to low salinity, whereas GHR mRNA levels did not differ. These results suggest that PRL is an important hormone for flounders that are acclimated to brackish water and it may control ion homeostasis with PRLR in the osmoregulatory organs.

• Fisheries and Aquatic Sciences
• /
• v.14 no.2
• /
• pp.123-129
• /
• 2011

To determine whether rearing density affects the hypermelanosis on the blind side (ambicoloration) of olive flounders Paralichthys olivaceus, we reared fry with an unpigmented non-eyed (blind) side in duplicate at densities of 150 individuals/$m^2$ (commercial production density: control) and 450 individuals/$m^2$ (high density group) for 90 days in 1-t dark-green fiberglass reinforced plastics (FRP) tank. We recorded feed intake, feed conversion efficiency (FE), growth and survival, and measured the ratios of staining blind-side area (staining area) and ambicolored fish every 30 days. Daily feed intake (DFI), feed conversion efficiency (FE), growth rate, condition factors, and survival rate were calculated at the end of the experiment. Although the FE was higher in the high-density compared to the control, the two density groups showed similar feed intakes, growth, and survival. The ratio of staining area as well as the ratio of ambicolored fish significantly were significantly higher in the high-density group than in the control from days 30 to 60, but significantly increased and evened out by the end of the experiment (P<0.05). In conclusion, we determined that rearing density is not the main cause of the blind-side hypermelanosis, but found that increasing the rearing density can accelerate the ambicoloration in olive flounders.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.51 no.4
• /
• pp.614-623
• /
• 2015

This study aims to estimate the Green-House-Gas emissions from domestic farmed flounder in the southern sea and Jeju-Do, where is mainly produced, by the assessment of energy consumptions and GHG emissions from domestic fish farms for establishing reduce standards of greenhouse gas from a sustainable perspective. It needs to analyze such GHG emission components as feed, electricity, fuel, fixed capital, fish respiration, and liquid oxygen in two locations by 4 stage running water type farm size of small, small and medium, large and medium, large scale. The result showed that the mean GHG emissions were $36.83kg{\cdot}CO_2/year$ in the southern sea and $24.33kg{\cdot}CO_2/year$ in Jeju-Do, respectively, in the stage of production per fish 1kg at 2 locations and farm size from domestic farmed flounders, and it will give to be useful for policy, planning, and regulation of aquaculture development with establishing GHG reduction standards.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.43 no.5
• /
• pp.451-456
• /
• 2010

This study was conducted to evaluate the quality characteristics (proximate composition, fatty acids, amino acids, sensory and textural properties) of whole body and dorsal muscle of olive flounders fed extruded pellets (EP) compared to raw fish-based moist pellets (MP). The olive flounders in this study were reared from 300 g to 1000 g for 7 months by feeding either EP or MP. The fatty acids and total amino acids of the whole body and dorsal muscle of the fish were similar among both groups. The major fatty acids in whole body and dorsal muscle werepalmitic acid and oleic acid. Finally, no significant differences were observed between groups for sensory and textural properties of the muscle. These results suggest that EP could be developed to replace MP without adverse effects on olive flounder quality.

• Fisheries and Aquatic Sciences
• /
• v.24 no.8
• /
• pp.277-283
• /
• 2021

Kudoa septempunctata has been reported as a new parasite in aquacultured olive flounder Paralichthys olivaceus, and also as a causative agent of food poisoning in humans. This paper investigated the infection of K. septempunctata in 216 sashimi and 20 sushi made of olive flounders in Busan, Korea. Among 236 samples, K. septempunctata was detected in eleven sashimi with 6-7 polar capsules by the microscopy. Among eleven sashimi, five sashimi were positive in Polymerase Chain Reaction (PCR) assay with the targets of 18S rDNA and 28S rDNA. The genotype of all the five PCR results is identified as the genotype ST3 which is common in Korea. K. septempunctata was found in olive flounders sashimi from Samcheonpo and Wando outside of Jeju Island. These findings would contribute to establish the standard of K. septempunctata for preventing food-borne outbreaks in advance and providing further preventive management for the seafood safety.