• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.4
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• pp.359-365
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• 2011

This study was conducted to investigate the production, elver stocking, rearing facilities and rearing method of eel culture to determine aquaculture management conditions for optimal rearing of eel Anguilla japonica. The production of eel culture was evaluated by the proportion of eels from the main inland fin fish species production in Korea. Elver stocking was assessed by the elver stocking densities of pond and recirculation culture. Rearing facilities were investigated according to the rearing tank size proportion of the pond and recirculation culture. We selected sample farms by region and by size. We visited sample farms and recorded the number of elvers stock for pond area, size of tanks, feed and feed quantity, and the size and number of harvest eels. The production capacity of Jeollanam-do and Jeollabuk-do were 71.9% and 21.3% respectively. This production quantity represented 93.2% of the total Korean eel production quantity. In Jeollanam-do, there are 236 eel farms, 202 pond farms, and 34 recirculation aquaculture facilities. The elvers' first density data by each aquaculture method revealed that elvers' first density varied more in recirculation system farms, as compared to pond aquaculture. In intensive pond farms, the elvers' first density decreased as the size of farm increased. There was a correlation between the size of tank(x) and the facility of a water wheel for dissolved oxygen in pond culture systems(y=0.022x-0.494; $R^2$=0.860). Another strong correlation was found between the weight of eel(x) and eel density(y) in pond culture systems(y=283.5x-0.27; $R^2$=0.992). Finally, there was a strong correlation between the length of eel(x) and the weight of eel(y) in intensive pond culture(y=0.0005x-3.2783; $R^2$=0.9775). The final survival rate did not differ significantly among pond sizes and culture types.

• The Korean Journal of Malacology
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• v.27 no.4
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• pp.337-343
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• 2011

In order to know the effects of rearing conditions such as water temperature, salinity, larval stocking density, kinds and amounts of food organism and seedling collection method on seedling production of the brackish water clam, Corbicula japonica, the growth and survival rate of the larvae were investigated at each rearing condition. The shell length of larvae showed faster growth at $24^{\circ}C$ and $27^{\circ}C$, and survival rate showed good results at $18^{\circ}C$ and $21^{\circ}C$. Based on growth and survival rate according to water temperature, the optimal water temperature for larvae rearing was $24^{\circ}C$. At the salinity of more than 3 psu, the growth and survival rate were higher than 0 psu. The optimal salinities for larvae were 6-9 psu. Growth and survival rate of larvae were high at low stocking density and the optimum stocking density of larvae was 10 inds./ml. Daily feeding concentrations of 10,000-20,000 cell/ml of food organisms mixed Pavolva lutheri, Isochrysis galbana and Chaetoceros calcitrans were very effective. Full grown larvae collection from various substratum was significantly higt in sand, especially sand size was less than 0.25 mm.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.6
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• pp.492-497
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• 2004

Waste concentration and waste generation rate in seawater aquaria by common conger (Astrocongey myriaster) and olive flounder (Paralichyhus olivaceus) were investigated. The initial fish density of common conger and olive flounder were $3{\%}\;and \;2.8{\%}$ of total weight of aquarium water, respectively Wastes in the seawater aquaria, such as protein, total suspended solid (TSS), ammonia, turbidity and chemical oxygen demand (COD) increased with days after stocking. Protein generation rate of common conger increased until 1 day after stocking while that of olive flounder increased until 3 days. The average protein generation rates of common conger and olive flounder were $0.28g/kg{\cdot}day\;and\;0.21g/kg{\cdot}day$, respectively. The trends of other waste generation rate were similar to protein generation rate.

• The Korean Journal of Malacology
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• v.31 no.2
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• pp.93-101
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• 2015

The effects of different stocking densities on the growth and survival rate of the 3-year-old pacific abalone, Haliotis dicus hannai were investigated in marine net cage for a year. Stocking densities in net cage ($2.4{\times}1.2m$) was set 15, 30, 45 and 60 percentage (= per)/sq m (square meter, $m^2$) with share to cross-sectional area per shelter. The water temperature during the testing period was $8.2^{\circ}C-22.1^{\circ}C$, and salinity is $33.5{\pm}0.6psu$, and dissolved oxygen is $7.87{\pm}0.86mg/L$. In the shell length (initial size : $71.50{\pm}2.28mm$) growth and shell breadth (initial size : $46.43{\pm}2.28mm$) of the test abalones, the absolute growth rate (ARG), daily growth rate (DGR) and specific growth rates (SGR) of the 15 per/sq m and 30 per/sq m were higher than those of 45 per/sq m and 60 per/sq m density group (P < 0.05). Also in the weight (initial weight : $35.7{\pm}8.1g$), it showed the same results. In survival rates, it were that 15 per/sq m and 30 per/sq m is significantly higher than 45 per/sq m and 60 per/sq m. Therefore, it was that the 15 per/sq m is optimized stocking density in marine net cages about the 3-year-old pacific abalone over 70 mm size. The result shown that total cross-sectional area under the shelter is based on 15 per/sq m ($2.4{\times}2.4m$, 354 number in a net cage) is suitable for fast growth and survival. But if the economy consider, optimized stocking density would be appropriate to accept 30 per/sq m ($2.4{\times}2.4m$, 710 number in a net cage).

• Korean Journal of Ichthyology
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• v.30 no.4
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• pp.194-204
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• 2018

In order to minimize the damage on the red sea bream Pagrus major by a harmful dinoflagellate Cochlodinium polykrikoides, we investigated the effect of feeding, starvation and stocking density on the survival rate, growth, growth restoration and physiological response of P. major exposure to C. polykrikoides. The experimental groups were divided into three groups such as F-HD (feeding and high density with $6.4kg/m^3$), S-HD (starvation and high density with $6.4kg/m^3$) and S-LD (starvation and low density with $3.2kg/m^3$) according to stocking density and starvation in marine cage ($11m{\times}11m{\times}5m$). The F-HD was fed throughout the experiment for 9 weeks, whereas S-HD and S-LD were not fed for 5 weeks and then refeeding for 4 weeks. Survival rate was the lowest in F-HD (85.5%) and S-LD was the highest (97.3%). The growth rates of S-HD and S-LD were significantly lower than F-HD during starvation period for 4 weeks, but rapidly recovered after feeding. The nutritional status such as ALB, TP, TCH, TG were similar to tendency of growth data. Ht, Hb, AST, ALT and GLU levels were significantly higher in the F-HD than in the starvation groups at the same time (in 3 week) during starvation period. But starvation groups did not differ during starvation period. As a result, F-HD is more sensitive to stress than S-HD and S-LD. Thus, during C. polykrikoides bloom period, starvation and stocking density control can help survival and growth restoration of the red sea bream.

• Fisheries and Aquatic Sciences
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• v.26 no.11
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• pp.660-668
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• 2023

This study aimed to investigate the growth performance of far eastern catfish (Silurus asotus) on outdoor fish farms to obtain basic data for the domestic eastern catfish aquaculture industry. An outdoor fish farm was directly monitored from June 2018 to October 2019 to determine the farming conditions, growth performance, and water quality. The growth performance in 2017 was analyzed using data from the same fish farm. Three years of monitoring showed that the fish farm required approximately 5-6 months between stocking, harvesting, and selling an S. asotus batch. The growth parameters, namely, the weight gain rate (WGR), specific growth rate (SGR) for culture periods, SGR for feeding periods, and feed coefficient rate (FCR), were 4,664.7%, 1.27%, 2.43%, and 1.25 in 2017; 6,452.0%, 1.52%, 2.79%, and 1.42 in 2018; and 3,270.0%, 1.11%, 2.12%, and 1.38 in 2019, respectively. Moreover, the WGR was two-fold higher in 2018 than 2019, whereas the FCR was more effective in 2019 than 2018, presumably because of the stocking density. No mass mortality was observed during the water quality analysis. The results of this study provide basic data for the development of the catfish industry.

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

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.1
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• pp.24-32
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• 2004

A mathematical model is used to investigate nitrogen dynamics in the intensive aquaculture ponds in the western coast of Korea. Parameters associated with water quality, sediments and growing of shrimp (Fenneropenaeus chinensis) are measured to calibrate the model for feeding ponds A and B and storage ponds. The model describes the fate of nitrogen including loadings of ammonia from feeds, phytoplankton assimilation, nitrification, sedimentation, volatilization and discharge. The model obtains good agreements with the measured values of TAN $(NH_4,\;NH_3),\;NO(NO_2,\;NO_3)$ and Chl (chlorophyll a). Impacts of water exchange on TAN and Chl are investigated, showing that the range of 0.01-0.2 (/day) cannot effectively reduce TAN but reduces Chl. Nitrogen in the ponds A is removed by sedimentation $66\%,$ volatilization $8\%,$ discharge of particulate and dissolved $8\%.$ The pond B shows $56\%\;and\;26\%$ of sedimentation and volatilization, respectively, to yield $10\%.$ decrease and 8c/o increase compared to those in the pond A. While the pond A has larger area (1.02:0.66 ha) and same stocking density (0.025 md./L) at the beginning of culture, the pond B obtains higher stocking density (0.0065:0.0091 md./L), longer feeding period (103:121 day) and resultant higher shrimp production (1.15:2.13 t/ha/cycle) at harvest. This is possibly due to the hydraulic characteristics driven by paddlewheels. At low ratio of the low speed area and the pond area, the rate of sedimentation is high, while the rate of gas exchange is low. Thus, the measurement and model analysis suggest that water quality and shrimp production are positively correlated with the hydraulic characteristics in the shrimp ponds.

• Journal of Animal Environmental Science
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• v.12 no.2
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• pp.51-60
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• 2006

Studies were carried out using growing to finishing pigs to investigate adequate floor space ($m^2/pig$) in Jeju environment. A randomized block design was used to compare the effect of pig performance on 3 stocking rates (low $0.56 m^2/pig$, medium 0.70 and high 0.90). Liveweight gain and feed intake were measured over a 4 week(Growth stage 1 and Growth stage 2) period or a 3 week(Growth stage 3) period. In growth stage 1 (43 to 65 kg body weight ; BW), daily weight gain was significantly higher in the medium stocking rate than in low or high (P<0.05). However, no significant difference in daily weight gain was found among treatments in growth stage 2(65 to 91 kg) or 3 (91 to 105 kg). Dressing percentage, back fat thickness and carcass grade were also not different (P>0.05). In conclusion, daily weight gain of pigs reared in medium density appeared to be higher than in the other groups during the early growing period which is $0.70m^2/pig$ and similar to that recommended by National Livestock Research Institute, RDA.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.6
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• pp.869-874
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• 1998

A feeding trial was carried out to investigate the optimum density of juvenile abalone (Haliotis discus hannai) fed the formulated diet or macroalgae ( Undaria). Abalone with initial average shell length of 8.41 mm were stocked into three replicate tanks at four different densities of 1430, 2860, 4290, and 5720 individual/$m^2$ for 15 weeks. The formulated diet produced higher body weight and shell growth, soft body weight and survival rate than Undaria in abalone. Abalone fed the formulated diet have significantly (P<0,05) higher lipid and ash, and lower moisture and protein in soft body. Higher density resulted in lower growth and survival (P<0.05). Whereas shell growth, survival rate and weight gain were not significantly (P>0.05) different within the abalone stocked at stocking densities of 1430 and 2860 individual/$m^2$ in each diet group. Body composition of abalone was not affected by increasing density. These study indicate that the number of abalone (shell length ranges of between 8 mm and 17 mm) below 2860 individual/$m^2$ were predicted to effective density in the indoor tank culture system.