• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.6
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• pp.796-800
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• 2014

A feeding trial was conducted to investigate the growth and body composition of juvenile sea cucumber Apostichopus japonicus in integrated culture with abalone Haliotis discus hannai or rockfish Sebastes schlegeli. Triplicate groups of sea cucumber averaging $1.2{\pm}0.05g$ were cultured alone or with abalone or rockfish for 12 weeks. Survival of sea cucumber was not affected by co-culturing (P>0.05). Weight gain of sea cucumber cultured with rockfish was significantly higher than that of sea cucumber cultured alone (P<0.05), and did not differ from that of those cultured with abalone (P>0.05). These findings indicate that co-culturing sea cucumber with rockfish effectively improves the growth of sea cucumber.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.2
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• pp.161-167
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• 2016

The effects of fermented fecal solid diets on the growth of the sea cucumber Apostichopus japonicus was investigated in a recirculating aquaculture system (RAS) during a 90-day experiment at 16.5-17.5℃, 32±0.5 psu salinity, pH 7.9-8.2, and 5.2-7.1 mg/L dissolved oxygen. The aim was to determine the feasibility of RAS fecal solid waste as a renewable feed for A. japonicus. In this study, unfermented fecal solid (UF), fermented fecal solid (FF), and commercial feed (CF) diets were used. The results showed that the growth rate did not differ significantly (P>0.05) between A. japonicus fed FF and CF; however, the growth rates of A. japonicus fed FF and CF were ~50% higher than that of those fed UF. Thus, utilization of fecal solid by A. japonicus may overcome the problem regarding accumulation of RAS waste. Use of a fermentation process would improve utilization of fecal solid as a renewable food source for A. japonicus.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.3
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• pp.343-350
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• 2016

The sea cucumber Apostichopus japonicus is a commercially valuable aquaculture species in Korea. Aquaculture species require specific nursery culture conditions to increase survival and growth rates. Sea cucumbers hibernate during the high temperatures of summer and during the low temperatures of winter, and suboptimal temperature conditions decrease sea cucumber growth and survival rates. The natural South Korean environment is very unfavorable for culturing sea cucumber; therefore, developing a recirculating aquaculture system (RAS) capable of breeding and growing sea cucumber year-round is necessary. The aim of this study was to investigate growth performance of juvenile sea cucumber in a RAS. Growth and survival rates of juvenile sea cucumber were high during our 24-week experiment. Sea cucumber survival rates were 87.8-93.3%, and specific growth rates were 0.4689-0.7846.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.6
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• pp.785-789
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• 2014

An experiment was conducted to investigate the effects of feeding by different feed types (powder, crumble and pellet) of two different feed formulations with simple dried (D) or extruded (E) conditions on growth and body composition of juvenile sea cucumber Apostichopus japonicus. Triplicate groups of sea cucumber averaging $1.2{\pm}0.05g$ were fed each of the D1, D2, EP1 or EP2 diets for 12 weeks. Survival of sea cucumber fed D2-crumble was higher than that fed EP2-crumble diet (P<0.05). Weight gain of sea cucumber fed EP1-powder was higher than that fed EP1-crumble and EP2-crumble diets (P<0.05). These findings indicated that simple dried feed could use independently feed type for sea cucumber culture and powder type of extruded feed is also good for sea cucumber culture.

• 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 Environmental Biology
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• v.33 no.4
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• pp.433-440
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• 2015

The Apostichopus japonicus is an important species in some Asia countries including Korea, China and Japan. The purpose of the present study was to investigate the differential gene expression of heat shock protein90 (Hsp90) and ferritin as a biomarker for the thermal stress during water temperature rising in the sea cucumber, A. japonicus. The A. japonicus (1.4 g) was cultured in incubator of separate temperature ($15^{\circ}C$, $20^{\circ}C$, $25^{\circ}C$ and $30^{\circ}C$) for each 0, 3, 6, 12, 24, 48 hours. The mRNA expression levels of Hsp90 and ferritin were examined using RT-PCR assay. Results showed that, the expression of Hsp90 mRNA was not significantly changed at $15^{\circ}C$. The expression of Hsp90 mRNA was significantly increased at high temperature such as $20^{\circ}C$ and $25^{\circ}C$. Furthermore, Hsp90 mRNA was early increased at $25^{\circ}C$ than $20^{\circ}C$. The ferritin mRNA was similar expression pattern with Hsp90. But, Hsp90 mRNA was more sensitive than ferritin mRNA at high thermal stress. These results indicate that Hsp90 and ferritin mRNAs were involved in the temperature changes response and may be play an important role in mediating the thermal stress in A. japonicas.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.1
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• pp.26-29
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• 2016

This study investigated the effects of dietary inclusion of sea mud on growth and body composition of juvenile sea cucumber Apostichopus japonicus. In experiment 1, three experimental diets containing sea mud at the level of 0, 30 and 60% were prepared. After feeding trial for 7 weeks, survival was not significantly different among groups. Final mean weight of sea cucumber fed the experimental diet without sea mud supplementation was significantly higher than that of sea cucumber fed the diet containing 30 and 60% sea mud. In experiment 2, three experimental diets containing sea mud at the levels of 0, 15 and 30% were prepared. After feeding trial for 19 weeks, survival was not significantly different among groups. Final mean weight of sea cucumber fed the diet without sea mud supplementation was not significantly different from that of 15%, but was significantly higher than that of sea cucumber fed the diet containing 30% sea mud. It was concluded that dietary inclusion of sea mud may inhibit growth of sea cucumber.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.4
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• pp.474-485
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• 2016

This study compared the fatty acid composition of wild and cultured specimens of the sea cucumber Apostichopus japonicus. We extracted total lipids from the specimens and determined their fatty acid compositions through capillary gas chromatography, resulting in the identification of 53 fatty acids. We found that wild sea cucumbers were rich in palmitoleic (C16:1n-7) and eicosapentaenoic acid (C20:5n-3), whereas cultured specimens were rich in eicosenoic (C20:1n-9) and arachidonic acid (C20:4n-6). In both types of sea cucumbers, the highest percentage of polyunsaturated fatty acids (PUFA) consisted of polar lipids (PL), followed by total lipids (TL) and neutral lipids (NL). Cultured sea cucumbers contained a higher percentage of total lipids (TL) than wild sea cucumbers did, whereas there was no significant difference between the two groups in the percentages of neutral (NL) and polar lipids (PL).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.4
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• pp.366-371
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• 2017

Six experimental diets for juvenile sea cucumbers Apostichopus japonicus were evaluated and compared with current commercial diets. Sea cucumbers (50 per tank; initial mean weight $2.3{\pm}0.1g$) in three replicates of seven groups were fed one of six experimental diets (ED1, 20% wild-harvested Sargassum thunbergii powder; ED2, 20% commercial S. thunbergii powder; ED3, 20% Undaria pinnatifida and Ascophyllum nodosum powders; ED4, 40% U. pinnatifida and A. nodosum powders; ED5, 10% brewer's yeast; and ED6, 10% sea shell powder) or a commercial diet (CD) for 28 weeks. The survival rate in all groups was 85-94%, with no significant difference among the experimental groups. The mean body weight of the sea cucumbers was significantly different among the experimental groups 6 weeks after the feeding trial. The final mean weight of the sea cucumbers was highest in ED1, ED3, and ED4, followed by ED6, ED5, ED2, and CD, in decreasing order. The results of this study suggest that U. pinnatifida and A. nodosum powders could provide a substitute for the S. thunbergii powder commonly used in commercial sea cucumber diets. Thus, the EP4 diet formulation, which contains no S. thunbergii, could be used as a practical feed for juvenile sea cucumbers.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.4
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• pp.400-407
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• 2019

The optimum growth temperature of sea cucumber is $18^{\circ}C$, above $20^{\circ}C$, the appetite declines and the digestive tract is atrophied. At $25^{\circ}C$ or more, it is known that the digestive tract is degenerated as growth is stopped by minimizing metabolic activity. Because of these physiological and ecological characteristics, the growth period of sea cucumber Apostichopus japonicus is relatively short in the natural environment of Korea where four seasons are clear. Therefore, maintenance of water temperature in sea cucumber culture is very important. This experiment was conducted to investigate the growth and lipid compositions of sea cucumbers at high temperature. Results showed that the growth and survival rates of sea cucumber were not significantly different until $26^{\circ}C$ (P>0.01). The fatty acid compositions of total lipid of sea cucumber tended to increase with saturated fatty acid content and decrease with n-3 fatty acid content at higher water temperature.