• 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.

• 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.48 no.4
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• pp.403-410
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• 2015

Viral nervous necrosis (VNN) is a serious disease of sevenband grouper Epinephelus septemfasciatus in Korean aquaculture farms. However, we suggest the following preventative methods for hatcheries: 1) disinfecting rearing water, 2) selecting spawners via ELISA and PCR, 3) selecting eggs via PCR, 4) disinfecting fertilized eggs, and 5) proper facilities management. When these methods are implemented, nervous necrosis virus (NNV)-free fish are produced because vertical and horizontal transmission is prevented. However, horizontal transmission of NNV through rearing seawater sourced from the environment during grow-out stages in sea cages can still occur. Live NNV vaccines with a low rearing temperature or Poly(I:C) immunization are very effective at preventing horizontal transmission of NNV in rearing farms. Furthermore, even after VNN is contracted, fish mortality can be reduced by administering Poly(I:C).

• Journal of Aquaculture
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• v.8 no.2
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• pp.117-131
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• 1995

In order to improve the present running seawater system for seedling production of marine fishes, rearing experiments with the juveniles of black seabream (Acanthopagrus schlegeli) and oblong rockfish (Sebastes oblongus) were conducted. The recirculating seawater system (F) equipped with the rotating biological contactors and the running seawater system (R) were used. Environmental factors, growth, survival rate and rearing density of the fish were compared between two systems during the experimental period. In the rearing experiment of black seabream, water temperature in F was fluctuated with surrounding air temperature and was higher than that in R. Specific gravity of the rearing seawater in F was relatively stable in the range of 1.0252 to 1.0266, while that in R was greatly fluctuated. pH in F turned out to be 7.51, but pH in R was similar to that in the natural seawater. Dissolved nitrite and nitrate in F were higher than those in R. While no significant differences in the growth of black seabream juveniles were recognized between two systems, survival rates of fishes in F were higher than those of fishes in R. In the rearing experiment of oblong rockfish, water temperature in F was higher than that in R. Specific gravity in F was slightly higher than that in R which showed relatively less fluctuation in the range of 1.0253 to 1.0270. pH in F turned out to be 7.96, but pH in R was similar to that in the natural seawater. Dissolved nitrite and nitrate in F were higher than those in R, but ammonia was lower in F. The juveniles of oblong rockfish reared in F grew significantly faster in their total length and body weight than those in R (P<0.05). However, survival rates of fishes between two systems showed no significant differences.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.4
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• pp.457-468
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• 1995

In order to develop a more practical culture system from the present running seawater tank system, two experiments of environmental factors, growth, survival rate and rearing density of olive flounder (Paralichthys olivaceus) were carried out for two consecutive years. Two groups of fish in initially averaging 7.5cm of total length, and 3.4g of body weight (EXP. I) and 5.0cm and 1.8g (EXP. II) were reared in the semi-closed recirculating seawater system equipped with the rotating biological contactors with the commercial culture scale. The dissolved inorganic nitrogen concentrations is EXP. I ranged 0,247-0.512 ppm of $NH_4-N$ (0.010-0.043 ppm of$NO_2-N$, and 0.108-0.342 ppm of $NO_3-N$, and those in EXP. II were 0.091-0.715 ppm, 0.002-0.045 ppm, and 0.007-0.277 ppm, respectively. Daily feeding rates of the fish were $0.67-2.41\%$ in EXP. I and $0.69-2.22\%$ in EXP_ II, and teed efficiency were $34.8-59.8\%\;and\;40.5-88.4\%$ in EXP. I and II, respectively. The average total ten說h and body weight were 40.0-42.8cm and 695.0-852.69g after 340 days culture in EXP. I, and 36.7-39.7cm and 552.4-706.4 g after 365 days culture in EXP. II, respectively. Survival rates of the fish at the end of EXP. I and II were $92.0\%\;and\;96.0\%,$ respectively. The ratio to body surface area of non-ocular side in all fish to bottom area of rearing tank, so-called covering rate, was used as an indicator of rearing density. The highest cowering rate and weight density of fish per $m^2$ of rearing tank at the end of experimental period were 2.2 and 34.1kg in EXP. I, and 2.6 and 36.3kg in EXP. II, respectively. For the commercial culture of olive flounder, the semi-closed recirculating seawater system was found to be more effective than the running seawater tank system in aspect to the fish productivity and protection of marine environment.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.6
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• pp.862-867
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• 2013

Since the industrial revolution, seawater has increased in temperature and acidity due to the increase in anthropogenic carbon dioxide in the atmosphere. To understand the effect of elevated $CO_2$ on the early life stages of fish, we reared fertilized eggs of black sea bream Acanthopagrus schlegelii under three $CO_2$ concentrations (400, 850 and 1550 ppm) for 3 weeks. The standard length and wet weight of black sea bream larvae declined with enhanced $CO_2$ concentration in the rearing water (P<0.05). However, chemical analysis using ICP-OES on internal tissues of black sea bream larvae indicated that the whole-body calcium concentration increased with $CO_2$ concentration in the rearing water. These conflicting results suggest that future experiments should examine the acid-base balance to investigate the formation of bone and otolith during larval growth.

• Korean Journal of Environmental Biology
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• v.19 no.2
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• pp.173-181
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• 2001

To find the appearance period and distribution of Edwardsiella tarda which causes severe damage to flounder (Paralichthys olivaceus) farms in Jeju-do, the rearing seawater (inflow, rearing water, outflow) and internal organs of flounders from 5 flounder farms were examined from June, 1997 to May, 1998. The number of bacteria in seawater was counted by plating the seawater on DSSS (Double Strength Salmonella-Shigella) agar plates or by plating after cultivation of bacteria. Bacteria in internal organs were counted by plating series of dilution of homogenized organ. The results are summarized as follows. E. tarda was detected in inflow seawater of five flounder farms in July, September and November, 1997 and February, March, April of 1998. In the rearing water and outflow water, the bacterium was detected throughout the year and the number of bacteria was much higher in summer than any other seasons. A large number of E. tarda in the internal organs were detected at farm B where a track-shaped tank was used, which has the characteristics of low circulation rate and bad discharge of excrement and residuals. In contast, none of E. tarda was detected at farm A where high circulation rate and good discharge of organic materials were applied. A few number of E. tarda at farm E were detected at the same condition as the farm A. A large number of E. tarda was observed in liver and intestines among the internal organs, and the number was higher from June to September in summer.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.4
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• pp.501-506
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• 1999

This study was conducted to evaluate the purification efficiency in rearing water of the land based fish farm by screen filter and ultra violet (UV) irradiation. Purification efficiency for rearing seawater has been examined with screen filter of 60 $\mu$m pore size and UV irradiation at dose of 0.5 $mWS/cm^2$ for 5 months. Purification efficiency by changing of temperature, salinity, pH, DO, total bacteria and Vibrio species in rearing seawater by filtering and UV irradiation were not significant during 5 months, However, the removing rate of suspended solid and turbidity of rearing seawater were $43.8\~45.6\%$ (average, $44,7\%$) and $29.2\~33.2\%$ (average, $31,3\%$) by filtering, respectively. Also, Purification efficiency for the $NO_3^{-}-N,\;NO_2^{-}-N,\;NH_4^{+}-N$ and $PO_4^{3-}-P$ were $21.3\~21.9\%$ (average, $21.6\%$), $24.1\~25.2\%$ (average, $24.7\%$), $17.6\~17.8\%$ (average, $17.7\%$) and $19.0\~20.4\%$ (average, $19.7\%$) respectively by the system used on this study.

• Development and Reproduction
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• v.13 no.1
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• pp.35-41
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• 2009

In the present study, we investigated the effects of rearing condition during the winter period on artificial maturation and reproduction of cultured female eel, Anguilla japonica. The female eel was adapted by combination of environmental conditions (seawater/low temperature, $10^{\circ}C$; seawater/high temperature, $20^{\circ}C$; freshwater/low temperature, $10^{\circ}C$; freshwater/high temperature, $20^{\circ}C$) during 8 weeks of the winter period. Then, the female eel cultivated by different conditions during the winter were transferred to seawater at $20^{\circ}C$ for induction of artificial maturation by salmon pituitary extraction (SPE) injection. The results shown that gonadosomatic index (GSI) and plasma levels of estradiol-$17{\beta}$ (E2) were significantly higher in female eel were reared in seawater than in freshwater, and were the highest at eel adapted by seawater/low temperature. Also, reproduction coefficient were higher in seawater/low temperature than in the other groups. These results will provide valuable information for elevation of the artificial maturation and reproduction coefficient in the cultured female eel.

• Animal cells and systems
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• v.11 no.2
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• pp.117-124
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• 2007

The present study demonstrates the changes in body weight (BW) and plasma sex steroid hormone profiles during artificial maturation induced by human chorionic gonadotropin (HCG) or salmon pituitary extract (SPE) injections in cultured eel, Anguilla japonica, kept in seawater for 3 months. In the weekly SPE-injected female group, BW was relatively stable during vitellogenesis. Following induction of vitellogenesis, females exhibited a rapid increase of BW, and the oocytes were observed to be in the migratory nucleus stage at the end of the experiment. Plasma testosterone (T) and $estradiol-17{\beta}$ ($E_2$) levels increased slightly during vitellogenesis and peaked at an average of 5.82 ng/mL and 4.76 ng/mL, respectively, at the end of the experiment. In the weekly control and HCG-injected female groups, BW slowly decreased during the experimental period, and the oocytes of the two groups were observed to be at the primary yolk globule stage. In the weekly HCG-injected female group, plasma T and $E_2$ levels increased slightly during vitellogenesis and decreased afterward. In the control female group, however, plasma T and $E_2$ levels were not altered during the experimental period. Furthermore, plasma $17{\alpha},20{\beta}-dihydroxy-4-pregnen-3-one$ (DHP) was not detected in all experimental groups. Fertility and hatching rates of SPE-injected females were significantly higher in those that ovulated 15 h after DHP injection than 18 h. These results indicate that long rearing in seawater increases responsiveness to SPE in ovarian maturation of the Japanese eel, resulting in shortened period from completion of vitellogenesis by sex steroid hormone production.