• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.4
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• pp.541-548
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• 2023

Behavior serves as an important indicator of the effects of environmental stressors on organisms. In this study, one-year-old abalone Haliotis discus hannai (15.1±0.8 mm) were used and each 0.34 m2 tank was stocked with 100, 150, 200, 250, and 300 juvenile abalone. After 328 days, we found that the low stocking density treatment showed significantly higher growth, whereas the high stocking density treatment showed significantly lower growth. In addition, abalone showed a lower rate of movement, distance moved, and velocity at higher stocking densities, but only velocity differed significantly. In contrast, In the Supplied the feed tanks significant difference between the moving distance and velocity. When the two groups of different sizes were mixed in tank, the rate of movement, distance moned, and velocity showed significant differences between differently-sized indivisuals. Our study indicates that breeding abalone at high densities has a negative effect on their growth and survival, which is thought to primarily be caused by spatial competition, and secondarily by differences in body size, ultimately affecting growth and productivity.

• Journal of Aquaculture
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• v.12 no.3
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• pp.213-220
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• 1999

This study was performed to investigate the effects of water temperature and stocking density and rotifer density on the mass production of larval red marbled rockfish, Sebastiscus tertius. Total length of the marbled rockfish larva grown in $23^{\circ}C$ of water temperature were 10.80mm, which was the best, while those grown in $29^{\circ}C$ of water temperature were 6.28mm, which was the lowest. The survival rates of red marbled rockfish larvae grown in $20^{\circ}C$ and $23^{\circ}C$ were 24.0% and 18.5%, respectively. However, the survival rate of red marbled rockfish larvae grown in $26^{\circ}C$ was $7^{\circ}C$ and no larvae survived in $29^{\circ}C$. The total length of red marvled rockfish larva stocked at the density of 5 and 10 larvaper liter of water were high, which were 11.52 mm and 11.22 mm, respectively, but those stocked at the density of 30 larva per liter of water were 7.55mm, which was the lowest. The survival rate of red marbled rockfish larva stocked at the density of 2.5 larva per liter of water was 52.0%, which was the best, but the lowest, 18.0% for the red marbled rockfish larva stocked at the density of 30 larva per liter. There was a trend toward decrease in survival rate of red marbled rockfish larva as their stocking density increased. The survival rates of red marbled rockfish larva fed rotifers at the density of 10 and 5 individuals per ml were high, 48.5% and 48.0%, and their total lengths were 11.92 and 11.89mm, respectively, which grew relatively fast. The survival rate and the total length of red marbled rockfish larva fed rotifers at the density of 30 individuals per ml were the lowest, which were 8.40mm and 21.5%, respectively. Also, red marbled rockfish larva fed rotifers at the density of more than 20 individuals per ml achieved poor survival and growth. These results indicated that the proper conditions for the mass production of larval red marbled rockfish were $23^{\circ}C$ of water temperature, fish larva stocking density of 5 to 10 larva per liter of water and rotifers density of 5 to 10 individuals per ml as live feed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.6
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• pp.747-752
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• 2011

The parrotfish Oplegnathus fasciatus is a sub-tropical species that is difficult to culture during the winter in South Korea. As a result, a recirculating aquaculture system (RAS) was developed to rear parrotfish. This study investigated the effects of stocking density and dissolved oxygen (DO) concentration on the growth and hematology of the parrotfish in the RAS. The experimental stocking densities were 5 (SD05), 10 (SD10), 15 (SD15), and 20 kg/m3 (SD20) total body weight to tank water volume. As the stocking density increased, the mean weight gain, feed efficiency, and specific growth rate tended to decrease. However, SD10 and SD15 did not differ statistically from SD05 in feed efficiency (P>0.05). Although better growth was achieved in SD05, SD10 and SD15 appeared to be acceptable, practically and economically, in terms of feed efficiency. The experimental DO concentration ranges were 3-4 (DO3), 5-6 (DO5), and 7-8 mg/L (DO7). The mean weight gain and survival tended to increase with the DO concentration, but there were no differences among treatments (P>0.05). Although the feed efficiency did not differ among the treatments, the specific growth rates and daily feed intake increased with the DO concentration and were the highest in DO7 (P<0.05). The cortisol concentration was the highest in DO3 (P<0.05), while there was no difference between DO5 and DO7 (P>0.05).

• Journal of Aquaculture
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• v.16 no.4
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• pp.257-261
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• 2003

The effects of different stocking densities on the growth of juvenile abalone, Haliotis discus hannai and water quality in the recirculating system with rotating biological contactor, were assessed. The trials were conducted using total weight 32 g juveniles abalone for 60 days at stocking densities of 5, 10, 15 kg/$m^2$. The animals were fed sufficient amounts of the pellet diet of 30.4% protein during the experimental period. Daily feeding rate (DFR) and survival rate (SR) of 5 kg/$m^2$ showed 0.76% and 85.5% those were not significantly differed 10 kg/$m^2$ showing 0.75% and 96.0% (P>0.05). DFR and SR of 15 kg/$m^2$ showing 0.38% and 31.2% were significantly lower than 5 and 10 kg/m2 (P<0.05). Daily growth rate (DGR) and feed efficiency (FE) showed the highest as 0.19% and 24.2% in 5 kg/$m^2$ the lowest as 0.05% and 14.3% in 15 kg/$m^2$ (P<0.05). According to, these results was an inverse relationship between growth and stocking density. The optimum density of juvenile abalone from this experiment is 5 to 10 kg/$m^2$ in the recirculating system.

• ALGAE
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• v.29 no.3
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• pp.217-225
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• 2014

Land-based seaweed (Gracilaria) cultivation systems may provide products with high quality and biosafety for human consumption, as well as for other high value applications. However, a limitation for this land based system is high management costs. The objective of this study was to determine if the management costs for Gracilaria cultivation can be reduced without a decrease in productivity by using $CO_2$ injection along with a high stocking density and high photosynthetically active radiation (PAR), and commercially available fertilizers. When Gracilaria tikvahiae was cultivated at a high stocking density and high PAR, coupled with $CO_2$ enhancement, the productivity was significantly higher than that at a lower stocking density, low light without $CO_2$ injection. We also found that G. tikvahiae grown in a medium of commercially available fertilizer (Jack's Special, JS) showed a similar growth rate and productivity to that grown in von Stosch's enriched (VSE) seawater, while the cost for JS media is only 2% of the cost for VSE. These results suggest that $CO_2$ injection and commercial fertilizer may be a potential way to provide sustainability in land-based Gracilaria cultivation systems.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.4
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• pp.380-387
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• 2023

Stocking density is associated with Paralichthys olivaceus growth; thus, fish should be rapidly reared at high densities for commercial reasons. Studies have reported that high stocking density retards growth; however, few have investigated the malformations caused by stocking density stress. This study compared the growth and malformation rates of P. olivaceus at different densities and stress- and immune-related gene expression between malformed and normal fish. Forty days post-hatching, fish (total length, 1.49±0.02 cm) were reared at 800 (low density; LD), 1500 (medium density; MD), and 4000 (high density; HD) fish/m², and the growth rate was measured weekly. On day 30, RNA was extracted from the kidneys, and the expression of stress-, immune-, and malformation-related genes was analyzed using qRT-PCR. The malformation rate in the HD groups was approximately three times higher (62%) than that in the LD and MD groups (approximately 20%), and growth was lower regarding length and weight. The stress-related (HSP70 and GPX) and immune-related (PIR and IgM) genes showed higher mRNA expression in the HD group and malformed fish than in the LD group and normal fish. However, TLR3 showed the opposite results. In summary, high stocking density suppressed growth and increased malformation risk in P. olivaceus.

• Ocean and Polar Research
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• v.32 no.1
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• pp.63-71
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• 2010

An experiment was conducted to investigate the effects of temperature and stocking density on daily patterns and rates of total ammonia nitrogen (TAN) excretion in juvenile red seabream Pagrus major (mean body weight: 29.0 g) under fasting and feeding conditions. Fish were acclimated over 7 days under four different temperatures (10, 15, 20, and $25^{\circ}C$) and at two different densities (5.5 and $11.0\;kg\;m^{-3}$). Each treatment had three replicates and a total of 216 fish were used. After 72 hours starvation, endogenous TAN excretion was measured for each temperature and density. To investigate exogenous TAN excretion, fish were handfed a commercial diet containing 51.6% crude protein twice a day for 7 days, at 08:00 and 16:00. Water was sampled from both inlets and outlets of chambers every 2 hours over a 24 hour period. Both endogenous and exogenous TAN excretion increased with increases in temperature and density (P<0.05). Mean daily endogenous TAN excretion rates at 10, 15, 20, and $25^{\circ}C$ were 88.8, 101.1, 125.0, and $143.3\;mg\;TAN\;kg^{-1}\;d^{-1}$ at low density, and 105.2, 119.2, 141.5, and $168.8\;mg\;TAN\;kg^{-1}\;d^{-1}$ at high density, respectively. Mean daily exogenous TAN excretion rates at 10, 15, 20, and $25^{\circ}C$ were 343.5, 403.7, 535.7, and $601.7\;mg\;TAN\;kg^{-1}\;d^{-1}$ at low density, and 391.9, 479.7, 611.9, and $683.4\;mg\;TAN\;kg^{-1}\;d^{-1}$ at high density, respectively. The exogenous TAN excretion rate peaked 10~12 hours after the first feeding under all temperatures and densities. The TAN loss for ingested nitrogen increased with increases in temperature and density (P<0.05), ranging from 27.9 to 50.1% at low density and 31.7 to 56.9% at high density. This study provides empirical data for estimating ammonia excretion and managing the culture of red seabream under the given temperatures and densities.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.5
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• pp.1407-1416
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• 2016

This study was conducted to investigated the effects of stocking density on growth and survival of sea cucumber, Apostichopus japonicus in the indoor multiple tank for 12 weeks. There were six treatments(stocking densities) in this experiment, i.e. 1, 2, 3, 4, 5 and 10 individuals per 10 L plastic aquarium($W41{\times}H24{\times}D11cm$, represented as D1, D2, D3, D4, D5 and D10, respectively). Each treatment had ten replicates. The results showed growth variation of sea cucumber, Apostichopus japonicus decreased with the increase of stocking densities. After the end of the experiment, no significant differences(P>0.05) between D1~D5 treatment group whereas significant differences(P<0.05) between D1 and D10 treatment group. Survival rate showed D1~D10 were 90%, 90%, 100%, 95%, 94% and 72%, respectively. Especially, significant differences(P>0.05) between D1~D5 and D10 treatment group. The results indicated optimum of stocking density for sea cucumber, Apostichopus japonicus within five individuals per 10 L plastic aquarium($0.05individuals/m^2$).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.5
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• pp.588-596
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• 2014

To examine the influences of water temperature and stocking density on feeding, growth and blind-side hypermelanosis of the starry flounder Platichthys stellatus, we performed an experiment with fry at two densities: 2 and 8 fish/L. The fry had a total length of $3.2{\pm}0.1cm$, body weight $0.6{\pm}0.1g$, and pigmented patches (pigmented ratio $2.6{\pm}0.4%$) on the blind side. Duplicate experiments were conducted in 93.7 L glass tanks for 120 days, from July to November. We determined daily food intake (DFI), food efficiency (FE), growth, survival rate, ratio of hypermelanic fish, and pigmented area rate on the blind side at 60-day intervals. The DFI was less than 50 mg/fish/day, and growth was delayed from July to September (water temperature [WT]> $20^{\circ}C$). After October, when WT < $20^{\circ}C$, the DFI increased significantly and the growth was accelerated, suggesting that the rearing temperature of starry flounder in artificial facilities should be < $20^{\circ}C$. While the FE, and survival did no differ between the two density groups, DFI and growth were significantly higher at 2 fish/L than at 8 fish/L. There was no difference in the pigmented area ratio between the two density groups. Although the hypermelanosis was not correlated with body size, the malpigmentation increased with growth. These results suggest that a high stocking density is not the main cause of blind-side hypermelanosis, although it can accelerate hypermelanosis in the starry flounder.

• Korean Journal of Poultry Science
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• v.41 no.2
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• pp.115-125
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• 2014

With Single Comb White Leghorn (WL) and Korean Native Chicken (KNC) breeds, we compared the stress response with chicken breeds that were subjected to a high stocking density. Stress response was analyzed by the quantity of telomeric DNA, the rate of DNA damage and the expression levels of heat shock proteins (HSPs) and hydroxyl-3-methyl-glutaryl coenzyme A reductase (HMGCR) genes on tissues and blood. The telomere length and telomere shortening rates were analyzed by quantitative fluorescence in situ hybridization on the nuclei of lymphocytes and tissues. The DNA damage rate of lymphocytes was quantified by the comet assay. The expression levels of HSP70, HSP90-${\alpha}$, HSP90-${\beta}$ and HMGCR genes were measured by quantitative real-time polymerase chain reaction in lymphocytes. There was no significant difference between KNC and WL in body weight, weight gain, telomere shortening rate and DNA damage rate. However, the growth rate significantly decreased in chickens raised under high stocking density conditions, as compared to the control group. The telomere-shortening rate, DNA damage and HSPs expression of the lymphocytes were significantly higher in the high stocking density group than the control. The stress condition and breeds had a significant effect on the expressions of HSP70, HSP90-${\alpha}$ and HSP90-${\beta}$ in lymphocytes, except HMGCR. The stress response of WL was higher than that of KNC, as analyzed to the expression of HSP70 and HSP90-${\alpha}$. Therefore, we concluded that the chickens which were exposed to a high stocking density had increased the individual physiological stress response regardless of breeds, and White Leghorns are more susceptible to stress condition than Korean Native Chickens.