• Fisheries and Aquatic Sciences
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• v.3 no.2
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• pp.88-96
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• 2000

The present study estimated the variation of early survival of chum salmon families with respect to temperature and size after transfer to seawater. Heritability for seawater tolerance of half-sib families was also estimated at 45 days after hatching. Gametes were collected from 6 male and 18 female chum salmon to make 18 paternal half-sib families. Seawater tests were carried out at 3, 7 and $12^{\circ}C$ of $32\%$ seawater and compared with freshwater. Survival was significantly affected by seawater temperature. The highest seawater tolerance was obtained in 45-day old chum salmon at $7^{\circ}C$ seawater and the lowest seawater tolerance was obtained at $3^{\circ}C$. Overall survivals in seawater tolerance at $32\%$ varied among families. There were significant variance in fry survival among females (P=0.0001), and among males (P=0.0001). The heritabilities of survival in seawater in chum salmon were estimated to be 0.32-0.34 for the sire components at 45 days after hatching in 1998.

• Journal of Aquaculture
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• v.14 no.1
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• pp.29-33
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• 2001

Total length and body weight of grey mullet were 6.4cm and 2.1g, respectively at the beginning of the experiment. After 60 days of rearing, body weight of the mullet(363%) was significantly higher in freshwater group than that (187%) in seawater group. However, the condition factor showed no significant differences between seawater (9.0%) and freshwater (8.8%) groups. Survival of the mullet was 98.3% and 64.3% in seawater and freshwater groups, respectively.

• 한국해양학회지
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• v.5 no.2
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• pp.65-72
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• 1970

The effect of fresh water and various concentrations of aged seawater on the survival of fecal pollution bacteria, Escherichia coli, type I, Aerobacter aerogenes type I, and Streptococcus faecalis type were determined. Survivals of bacteria were measured by the membrane silter technique. Three species of bacteria indicate more tolerance in fresh water than in seawater. After 14-day incubation in fresh water, survival rates of bacteria were 90% withe E.coli, 20% with A.aerogenes, and 0.6% with Str.faecalis. However, the survival rate of fecal pollution bacteria decreases as the concetnration of seawater is increased. Generally, the death rate of E.coli is least affected by concentration of seawater. A.aerogenes is eliminated more rapidly with higher concentration of seawater, while Str.faecalis marks rather slight variation of elimination in various concentrations of seawater. In 100- percent seawater (Cl 18.1 ), the days required for 99.9% elimination of bacteria were 4.5 days with A.aerogenes, and 6.5 days with E.coli and Str.faecalis.

• Journal of Aquaculture
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• v.18 no.2
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• pp.69-75
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• 2005

One 30-day feeding trial was conducted to examine the effects of dietary salt on seawater adaptability of rainbow trout (Onchorhynchus mykiss) fed three experimental diets containing 0% (control), 4% and 8% salt. The experimetal period included 30 days of feeding trial in freshwater, 3 days of the step by step seawater acclimation with-out feeding diets, and 21 more days of seawater adaptation period (not with all experimental fish) with feeding the basal diet. Growth rates from triplicate groups were determined fur 30 days of feeding trial. Blood samples were taken at the begining and at the end of feeding trial, and 3 times (on 1st, 4th and 8th day) of the seawater adaptation period. Daily survival rates of duplicate groups from three experimetal treatments were recorded for 21 days of the seawater adaptation period. Total average initial and final fish weight were $149.5{\pm}7.6\;and\;187.1{\pm}7.6g$. Feed efficiency of fish fed diets containing 4% and 8% salt were significantly better than those of fish fed the control diet. Average cumulative survival rates were 72, 80 and 88% from the control, 4% and 8% salt diets, respectively. Pulse rate per minutes decreased with dietary salt level. Serum $Na^+\;and\;Cl^-$ concentrations of fish fed 4% and 8% salt diets were significantly higher than those of fish fed the control diet (P<0.05), however, the concentrations were stabilized after 8 days of seawater adaptation. Serum cortisol, glucose, cholesterol and tryglyceride concentrations, and the osmorality of fish decreased with dietary salt level, these values were significantly lower than those of fish fed the control diet. These results indicated that the dietary supplementation of salt could have advantages for seawater adaptability of rainbow trout.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.5
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• pp.549-555
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• 2018

The objectives of this study were to confirm the nutritional requirements and improve the survival of the walleye pollock Theragra chalcogramma, a cold seawater fish, by enrichment. We analyzed the fatty acids and amino acids of fertilized pollock eggs before hatching, just-hatched larvae, larvae that had absorbed only the yolk sac, and larvae starved for 2 days after yolk absorption. For the survival improvement experiment, we administered docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and DHA-EPA enrichment. Fatty acid decreased DHA and EPA content. On the $30^{th}$ day, body growth was significantly greater in pollock given the EPA and DHA-EPA treatments (P<0.05). Larval survival at 20 and 30 days after hatching (DAH) was greatest under the DHA-EPA treatment (P<0.05). Survival was significantly lower under the EPA treatment at 10 DAH, but then increased to approach that seen under the EPA-DHA treatment (P<0.05). Therefore, we determined that reduced survival in hatchlings of high-mortality pollack could be improved by controlling EPA and DHA content during enrichment. We conclude that cold seawater fish must be given feed that meets their nutritional needs, which can be accomplished using newly manufactured enrichment products for the larvae of cold seawater fish, such as pollock.

• Journal of fish pathology
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• v.35 no.2
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• pp.185-193
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• 2022

This study investigated carnival behavior in the nursery stage of Fenneropenaeus chinensis. In order to suppress the carnival behavior and improve the survival rate, it was examined whether there was a carnivalism inhibitory effect according to the rearing water of shrimp. In addition, their blood physiological changes were observed. As a result, in the experimental group with the size difference of F. chinensis, the survival rate was the highest in the biofloc technology (BFT) rearing water of olive flounder (75%), and in the experimental group without the size difference, the survival rate was the highest in the seawater experiment group (93%). In both experimental groups, rate of carnival behavior was observed to be low in the fed experimental group regardless of the size difference of F. chinensis. As a result of blood cell analysis of F. chinensis according to the rearing water, the percentage of granulocytes was the highest in the BFT rearing water of flounder (75%) and the lowest in the filtered seawater group (66%). The proportion of semi-granulocytes was the highest at 11% in the shrimp BFT rearing water, and the lowest at 7% in the filtered seawater. The proportion of hyalinocytes was highest in filtered seawater (27%) and lowest in flounder BFT rearing water (16%). These results suggest that carnival behavior and blood composition of F. chinensis may be different depending on the conditions of the rearing water in the nursery stage.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.6
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• pp.753-758
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• 2011

The seawater adaptability of land-locked masu salmon Oncorhynchus masou masou via acclimation was examined for aquaculture purposes. The survival, blood chemistry, and histological changes of masu salmon (150 g) were measured after 7-, 15-, and 30-day acclimation periods. After a total of 60 days in seawater cultures that incorporated the various acclimation periods, survival was 83.5, 87.2, and 91.0% for the 7-, 15-, and 30-day periods, respectively; thus, survival increased with longer periods of acclimation. Feeding efficiencies were 32.1, 52.0, and 40.6% for the 7-, 15-, and 30-day periods, and specific growth rates were 0.14, 0.26, and 0.23%, respectively. Generally, masu salmon appeared to exhibit better growth performance after an acclimation period of 15 days. Cortisol concentrations [mean ${\pm}$ SD] for 7, 15, and 30 days of acclimation were $21.0{\pm}6.5$, $17.8{\pm}4.8$, and $21.2{\pm}5.4\;{\mu}g/dl$, with the lowest values occurring with 15 days of acclimation. Osmolarities were $359.2{\pm}26.1$, $350.4{\pm}29.2$, and $354.6{\pm}29.3$ mOsm/kg, and glucose concentrations were $60.7{\pm}20.7$, $72.9{\pm}17.3$, and $76.6{\pm}14.1$ mg/dl for the 7-, 15-, and 30-day acclimation periods, respectively (P < 0.05). The histological study revealed that both gills and both kidneys of the masu salmon exhibited middle- to end-stage and middle-stage lesions in the 7- and 15-day groups, respectively, whereas these organs only had early-stage lesions in the 30-day group in the final experiment. Therefore, the seawater acclimation of masu salmon should involve more than 30 days in seawater.

• Journal of Aquaculture
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• v.18 no.1
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• pp.37-44
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• 2005

This study was conducted to compare the physiological conditions of black porgy (Acanthopagrus schlegeli) when reared in freshwater (0 psu) and seawater (35 psu) during 90 days. In terms of stress response, there was no significant difference in cortisol levels of the fish reared either freshwater or seawater until 60 days. Although cortisol level of fish reared in freshwater(12.6$\pm$5.0 ng/ml) was significantly higher than in seawater (4.5$\pm$2.9 ng/ml) at the end of experiment, these values were stable levels as compared with that of non-stressed fish. No significant differences in plasma osmolalities were recognized between the fish reared in freshwater (346.7$\pm$4.6$\~$356.5$\pm$2.1 mOsm/kg) and seawater (350.0$\pm$2.0$\~$357.0$\pm$22.6 mOsm/kg). Normal structure of gill lamellae without histological damage or cell necrosis has been observed in the fish reared in freshwater. In connection with growth and survival rate, total length and body weight of fish reared in freshwater were slightly longer and higher than those of fish reared in seawater. Survival rate of black porgy reared in freshwater was slightly higher than that of fish reared in seawater, but there was no significant difference. The results suggest that black porgy is reared with normal growth rate in freshwater without stress.

• Journal of Environmental Science International
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• v.5 no.3
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• pp.329-335
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• 1996

This project studies marine Vibrio vulnificus in oysters in the marine environment and attempts to correlate this bacteria's presence within various environmental parameters; we design this study to determine how different storage temperatures affect the survival of V. vuinficus in oysters and whether V. vulnificus is able to persist in oysters after exposure to UV light-disinfected seawater. Experimental depuration systems consist of aquaria containing temperature-controlled seawater treated with UV light and 0.2 ㎛ pore size filtration. Results showed that depuration at temperatures higher than 25℃ caused V. vuinificus counts to increase in oysters. Throughout the process, depuration water contained high concentrations of U vuinificus indicating"that the disinfection properties of UV radiation and 0.2 ㎛ pore size filtration were less than 어e release of V. vuinificus into seawater, In contrast, when depuration seawater was maintained at 10℃, the numbers of V. vuinificus were very little and multiplication in oysters was inhibited.

• Journal of Korean Society on Water Environment
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• v.23 no.1
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• pp.12-18
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• 2007

Difference of total coliforms (TC) survival time of mixed samples (effluent were mixed by seawater or freshwater) were examined in various conditions. The time taken to achieve a 90% reduction in the TC concentration ($T_{90}$) of effluent, high initial TC concentration and low initial TC concentration samples indicated 143.9, 121.9 and 89.6 hours at $25^{\circ}C$, respectively. At $4^{\circ}C$, log removal rate after 336 hours were 0.96, 1.04, and 1.30. TC survival time of effluent-inoculated seawater sample was longer than that of effluent-inoculated freshwater sample in laboratory. At outdoor condition, TC inactivation curves of effluent-inoculated seawater or freshwater samples showed similar patterns. And both of them were greatly influenced by climate condition. There was not enough evidence that TC survived longer in freshwater than sea water. It was unlikely that the salinity of sea water contributed to the inactivation process of TC.