• 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 Ecology and Environment
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• v.47 no.2
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• pp.82-90
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• 2014

To assess the adverse effects of suspended solids on fishes, the hatching rate of embryo, and survival and growth of larvae were measured with common fish species of river such as crusian carp (Carassius auratus), common carp (Cyprinus carpio) and medaka (Oryzias latipes). Bioassay on hatching rate of embryo was conducted with a range of turbidity as 10 levels from 0.2 to 8,080 NTU. Another bioassay on 4-day larval survival and 21-day larval growth were also conducted with a range of turbidity as 8 levels from 0.1 to 8,260 NTU, and 6 levels from 0.7 to 2,030 NTU, respectively. The hatching rate of C. auratus was not significantly different from that of control at turbidity below 4,040 NTU, whereas it decreased when turbidity was 8,080 NTU (p<0.05). The hatching rate of C. carpio was not affected by concentration of suspended solids. For O. latipes, the hatching rate significantly decreased from 254 NTU (p<0.001) and it was zero when turbidity was 8,080 NTU. The 4-day survival of larvae of all 3 species was not affected by turbidity, while the larval growth of all 3 species was significantly affected. The turbidity effect on the growth of C. auratus and C. carpio was observed from 7 days after the exposure at turbidity level of 145, 143 NTU, respectively. The turbidity effect on the growth of O. latipes was observed from 14 days after the exposure at turbidity level of 254 NTU. The results of this study will provide the basic information for the derivation of water quality criteria on suspended solids for the protection of aquatic ecosystem and the quantitative ecological risk assessment of freshwater environment.

• Journal of Life Science
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• v.28 no.5
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• pp.563-568
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• 2018

The insect industry is a promising agricultural resource and expected to grow steadily. In Korea, Gryllus bimaculatus and the larvae of Tenebrio molior, Protaetia brevitarsis, and Allomyrina dichotoma were listed as general food ingredients. As interest in these edible insects increases, rearing techniques and nutritious food sources are needed for mass production. In this study, wheat bran, dog feed, and pig feed were investigated for their effects on the larval growth of P. brevitarsis and A. dichotoma. When fermented sawdust with 30% wheat bran was used, the larval survival rate of P. brevitarsis and A. dichotoma (p=0.244341 and p=0.007966, respectively) and growth rate (p=0.001400 and p=0.000051, respectively) were significantly lower than those of the control (fermented sawdust with no supplement). Therefore, fermented sawdust with a high density of wheat bran was inappropriate for both insects. When fed fermented sawdust with 2.5 or 5% of dog and pig feed, the survival rate and growth rate of the larvae were higher than those of the control. Interestingly, the maximum larval weight with 2.5% dog feed was increased by $3.35{\pm}0.10g$ and $32.59{\pm}0.79g$ for P. brevitarsis and A. dichotoma, respectively. In addition, the larval period of both was shorter than that of the control by 40 days or more. Therefore, it is considered that animal feed can be used as a feed source for these edible insects.

• Journal of Aquaculture
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• v.13 no.1
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• pp.69-78
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• 2000

Bioactivity growth and survival rte of yolk sac larvae in cultured black seabream (Acanthopogrus schlegeli) red seabream (Pagrus major) and olive flounder (Paralichthys olivaceus) to 5 different concentration (0, 25, 50, 75 and 100%) of water soluble fraction (WSF) of Kuwait crude oil were studied. The 75% and 100% of WSF concentration influenced negatively on the length growth of larvae in each species so the growth rates of total length in the concentration of WSF were significantly lower than those of control. The high concentration (50%, 75%, and 100%) of WSF influenced negatively not only on the swimming frequency and speed but also on the morphological abnormality of larvae. Red seabream larvae showed the highest rate of abnormality by WSF among the tested fishes. The fish larvae exposed during pre-and post-hatch (egg and larval stages) and during post-hatch (larval stage only) to the WSF were significantly influenced on their survival rate. The larvae of red seabream were more sensitive to WSF than those of black seabream and olive flounder. The survival rates of larvae exposed to higher concentration (50%, 75%, and 100%) of WSF were significantly lower than those of the control but those of the 25% group were not.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.6
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• pp.485-491
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• 2004

Spawning induction, egg development and larval growth of ark shell (Tegillarca granosa) (L.) were investigated. The most effective method of spawning induction was steady temperature increasing from$4^{\circ}C\;to\;28^{\circ}C$ with irradiation of sea water by UV after T. granosa was exposed to air at $4^{\circ}C$ Optimum condition for larval roaring was under the 32.4 psu and two temperature $regimes:\;28{\pm}1^{\circ}C\;and \;25{\pm}1^{\circ}C$. Fertilized eggs was demersal isolated eggs, and egg diameter was $60{\mu}$. D-shaped larvae appear about 20 hr after hatching with $94.1{\mu}$ in shell length and $86.7{\mu}$ in shell height. Ten days were required from hatching to umbo larva stage, of a mean shell length $125.2{\mu}$. On 25th day, the larva grew to $450{\mu}$ in shell length and began to settle on the bottom. Effect of temperature between $25^{\circ}C$ (control group) and $28^{\circ}C$ on larval growth was not different. Survival rate of larvae settled on the bottom was about $19{\%}$ in both temperatures conditions $(25^{\circ}C\;and\;28^{\circ}C)$.

• Journal of Life Science
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• v.29 no.9
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• pp.996-1001
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• 2019

Edible insects are reported to be rich in protein, minerals and vitamins, and much attention has been paid to them as a future food source. In Korea, they were massively reared and sold. In order to enhance the market value of edible insects for industrialized mass production, it is important to develop the safe and nutritious feed sources for rearing them are needed. In this study, a chlorella-free control feed (Exp1) and six experimental feeds supplemented with 0.5~2.0% liquid or powder types of chlorella were formulated. Protaetia brevitarsis and Allomyrina dichotoma, registered as food ingredients in Korea, were fed with the designed feeds and parameters of growth including larval survivorship, larval body weight, and larval period were analyzed. When chlorella added, larval survivorship was increased 2~13%(p>0.05) and 9~22%(p<0.05) in each beetle compared to the control. Interestingly, the larval period of chlorella powder-added groups was shortened by 24 days (Exp3, p<0.05) in P. brevitarsis and 19 days (Exp4, p<0.01) in A. dichotoma. Meanwhile, some parameters, crude protein, crude fiber, copper, zinc, potassium, magnesium, and phosphorous, in chlorella-added groups of P. brevitarsis were also higher than the control group. Therefore, chlorella could promote the larval growth performance of these two beetles and be used as a feed additive in rearing them.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.6
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• pp.551-556
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• 2002

We have experimentally evaluated the content of thyroid hormones (THs), the growth and activity of larval rockfish (Sebastes schiegeli) born from parturient mother fish injected with 20 $\mu$g/g BW of 3,5,3-triiodo-L-thyronine ($T_{3}$). There was no difference of L-thyroxine ($T_{4}$) levels between controls (sham control and control) and $T_{3}$ groups in yolk-sac larvae just born from broodstock, while $T_{3}$level of $T_{3}$ group was significantly increased compared with controls. In addition, the both larval $T_{3}$ and $T_{4}$ levels in $T_{3}$ group were always higher than those of control during experimental period. Also, there were significant differences in the development of larvae from the two groups. The larval growth in total length and body weight according to the elapsed days after parturition showed the linear and curve equations, respectively, and the slopes of $T_{3}$ group were significantly higher than those of control. The survival rate of larvae in $T_{3}$ group was higher than that of control. Although the survival rate in $T_{3}$ group under the condition of starvation was significantly depressed compared with the control, larval swimming index in $T_{3}$ group was higher than control. Finally, these findings suggest that the exogenous $T_{3}$ could be transferred into hatched larvae in parturient rockfish by maternal injection, and subsequently the exogenous hormone could play some roles on physiological metabolism of larvae after parturition and may confer a distinct advantage to the fragile larvae during the early developmental stage.

• Korean Journal of Ichthyology
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• v.32 no.2
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• pp.78-83
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• 2020

This study aimed to investigate the effects of different water temperature (5, 8 and 11℃) on egg hatch and larval growth of walleye pollock Gadus chalcogrammus to improve rearing techniques for this species. Survival of eggs maintained at 5℃ was higher than that of eggs maintained at 8℃ and 11℃. The greatest hatching rate was obtained for larvae maintained at 8℃. However, time to first, 50% and 100% hatch of eggs maintained at 11℃ was shorter than at 5℃ and 8℃. A higher survival was observed in larvae reared at 5℃ compared to 8℃ and 11℃ and the greatest growth was observed in larvae reared at 11℃ compared to 5℃ and 8℃ during the feeding trial. This study demonstrated the importance of water temperature, as it affects culture performance of eggs and larval pollock. The results from this study provides valuable information for further development of pollock aquaculture.

• Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.339-345
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• 2011

Although culture techniques for the abalone Haliotis discus hannai are well known, mass culture of the benthic microalgae that are essential live food for the abalone larvae is still not practiced. This study was conducted to identify the microalgal species suitable for the growth of early larvae of H. discus hannai. The growth and attachment rates of 31 microalgal species were examined. Acrylic plates were used as the substrate. Among the 31 microalgal species, nine showing high growth and attachment rates were selected and tested for their dietary values via factors including settlement, metamorphosis, and survival rates of abalone larvae. Tetraselmis hazeni and Rhaphoneis sp. induced the highest settlement rate (65-69%) in abalone larvae. The metamorphosis rate was highest (57%) in larvae fed Rhaphoneis sp. and was also significantly higher in larvae fed Oscillatoria splendida (29%) and T. hazeni (22%) than in those fed other species. The highest survival rate of the larvae during the 15 days after metamorphosis was 67% in those fed Rhaphoneis sp., followed by T. hazeni (42%) and O. splendida (35%). In conclusion, Rhaphoneis sp. is the most suitable diatom for use as a live food for the culture of early larvae of H. discus hannai. In addition, T. hazeni and O. splendida are also potential species to be further developed and utilized in larval culture.

• Journal of Marine Life Science
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• v.3 no.2
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• pp.67-73
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• 2018

This study was conducted to investigate the influence of environmental factors such as water temperature, salinity, rearing density and feeding amount on the survival and development of larvae in surf clam, Tresus keenae. As a result of this study, the optimum conditions of larval rearing were as follows. The optimum range of water temperature is 20℃ to 24℃, the optimum salinity is 30 psu, the optimum rearing density is 5 ind./ml and the supply of mixed feed organism for larva rearing such as Isochrysis galbana, Chaetoceros simplex and Tetraselmis suecica is 10×10⁴ cells/ml. The results of this study suggest that the optimum conditions of environmental factors in larval rearing of Tresus keenae contribute to productivity improvement through rapid growth and high survival.