• Development and Reproduction
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• v.16 no.4
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• pp.271-277
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• 2012

The effects of ovulation induction in ussurian bullhead, Leiocassis ussuriensis, were investigated by treating ussurian bullhead with hCG, LHRHa, GnRHa, ovaprim, and pimozide. hCG was injected to ussurian bullhead at 0.75% NaCl, 5,000, 10,000, 20,000, and 30,000 IU, respectively. The ovulation inducement rates were 100% in 20,000 and 30,000 IU. Fertilization rates were 82.7% and 79.8%. Hatching rates were 59.4% and 57.2%. Ovulation time was between 16-19 hr The concentrations of LHRHa injected were 0.75 NaCl, 50, 100, 200, 300, and $300{\mu}g/kg$. The ovulation inducement rates were 100% in 300 and $400{\mu}g/kg$. Fertilization and hatching rates were 84.9% and 68.4% at $200{\mu}g/kg$. The times to ovulation were between 23 hr and 34 hr. Ovaprim of 0.75% NaCl, 1.0, 1.5, 2.0, 2.5 and 3.0 ml/kg were injected to the abdominal cavity. The ovulation inducement rate was highest at 2.0 and 3.0 ml/kg to 92% and ovulation time was between 27-38 hr. LHRHa concentrations of 0.75% NaCl, 50, 100, 200, 300 and $400{\mu}g$ were injected with pimozide ($1,000{\mu}g$). Ovulation inducement rate was 100% from 200 to 400 IU with pimozide. Ovulation time was 22-36 h. Fertilization and hatching rates were 88.9% and 70.4% in $200{\mu}g/kg$ with pimozide.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.10
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• pp.147-155
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• 2002

In the stereolithography process, the accuracy of product depends on laser power, scan speed, scan width, scan pattern, layer thickness, resin characteristics and so on. Therefore, appropriate process parameters are required for an accurate prototype. This paper presents a method to determine the key process parameters, i.e., laser scan speed, hatching space, and layer thickness based on scan length, scan area, and layer slope. In order to determine these parameters, three neural networks are employed to represent operator’s experience and knowledge. Optimum values on scan speed, hatching space and layer thickness are recommended to improve the surface roughness and build time on the developed SLA machine.

• Development and Reproduction
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• v.11 no.2
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• pp.105-109
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• 2007

This study examined temperature effect in egg development and hatching of longtooth grouper, Epinephelus bruneus. Fertilized embryos was not growth after morula stage at $15^{\circ}C$, at 18, 21, 24 and $27^{\circ}C$, the required time from fertilized embryos to hatching were 70 h. 30 min., 44 h. 10 min., 29 h. 10 min. and 24 h. 30 min., respectively. The hatching rates at $24^{\circ}C$ were higher than the other conditions and the hatching was not occurred at $15^{\circ}C$. These results suggest that the water temperature range of egg development and hatching was $18{\sim}27^{\circ}C$.

• Journal of Aquaculture
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• v.20 no.4
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• pp.239-247
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• 2007

We studied spawning, hatching and larval growth of Amphiprion melanopus under laboratory conditions. Each time a fish spawned about 440 to 650 eggs. The eggs were hatched 9 days later. Nest colour of the eggs changed from clear yellow orange to greyish violet with processing of embryogenesis. With regard to spawning according to the substrates, the fish prefered red clay pot and ceramic pot to volcanic scoria and live rock. Hatching rate (%) of the eggs on the former substrates was significantly higher than that on the latter. The number of eggs varied with the food stuff supplied to the fish. The fish fed Tetra bits (commercial diet), meat of short necked clams and mussels, and astaxanthin showed significantly higher fecundity with 638 eggs than that fed only Tetra bits (477 eggs) or Tetra bits with meat of shellfish without astaxanthin ($549{\sim}553\;eggs$). Higher temperature ranging from 24 to $30^{\circ}C$ induced shorter incubation period and smaller total length, but higher hatching rate. The optimum salinity and L:D cycle with $60\;{\mu}mol$ photon $m^{-2}s^{-1}$ for hatching were 33 psu and 16:8, respectively. The newly hatched larvae about 4.6 mm in total length grew to 7.5 mm in one week, 18.8 mm in a month and 37.9 mm in 70 days after hatching.

• Journal of Aquaculture
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• v.6 no.4
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• pp.295-310
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• 1993

As a part for the development of effective mass production techniqne of the puffer, Takifugu rubripes. seedfish, an investigation was carried out in 1989. 1991 and 1992 to determine the optimum starting feeding time of rotifers as a starting food for the fish larvae, and to find out the influences of the light intensitiy and LD cycles on the Artemia consumption by the larvae. The optimum starting time of feeding with rotifer. Brachionus Plicatilis was 2nd to 5th day from hatching resulting in survival of $96.5\~90.0\%$. Optimum light conditions for maximum feeding for fish larvae with Artemia were 1000 lux in 6mm, 600 lux in 8mm, and 200 lux in total length of 10-12 mm larvae. Relationship between total length (X: mm) of fish (6-12 mm in total length) and light intensity (Y: lux) for maximum feeding was:Y=2200-200X (r=-1.000). Relationship between days from hatching (X) and total length (Y: mm) of puffer fry was :Y=1.6427+0.2540X(r=0.9814) for 3 to 36 days after hatching, Y=-33.1452+1.1867X(r= 0.9854) for 36 to 68 days after hatching. Survival rate for 68 days after hatching was $24.1\%$ and the range of water temperature during this period was $21.25\pm1.67^{\circ}C$.

• Korean journal of applied entomology
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• v.51 no.4
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• pp.371-376
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• 2012

This study was conducted to predict the hatching time of eggs of Lycorma delicatula, to select an effective environmentally-friendly agriculture material (EFAM) and to evaluate the attraction effect of brown sticky traps for controling of Lycorma delicatula nymph and adults. Eggs hatched 55.9, 26.8, 21.6 days after incubation at 15, 20, $25^{\circ}C$ with 14L:10D condition and the hatching rates of egg were 61.9, 57.8, 30.4%, respectively. At high temperature conditions, egg development periods were shorter and the hatching rate was lower. The relationship between temperature and developmental rate was expressed by the linear equation Y=0.0028X-0.0228, $R^2$=0.9561. The low temperature threshold of eggs was $8.14^{\circ}C$ and the thermal constant required to reach larva was 355.4 DD. According to this relationship, the mean estimated hatching date was $22^{nd}$ May. The effective EFAM was natural plant extract, sophora extract, derris extract to nymph and natural plant extract, pyrethrum extract, sophora extract to adult. Among three colors of sticky trap : brown, blue and yellow, the brown sticky trap was the most attractive to nymphs and adults of L. delicatula over a 2 weeks trial period. It suggested that the brown sticky trap could be a very useful and environment-friendly control method for nymphs and adults of L. delicatula.

• Development and Reproduction
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• v.18 no.4
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• pp.311-319
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• 2014

Newly hatched black porgy larvae (Acanthopagrus schlegeli) swam to the surface, with the mouth and anus still closed and were 1.90-2.11 mm (mean, 2.0 mm) in total length (TL). The larvae were 2.71-2.94 mm TL (mean, 2.82 mm) on day 2 after hatching. At this time, about two-thirds of the yolk was absorbed, the bladder and intestines had formed, and the mouth and anus were open. Total length was 4.32-4.66 mm (mean, 4.45 mm) at the post-larval stage on days 5-6 after hatching, and the yolk and oil globule were almost absorbed. The end of the notochord began to flex, and 6-8 caudal fin rays were visible. The larvae were 15.37-16.1 mm TL (mean, 15.83 mm) at the juvenile stage on days 30-32 after hatching, and the number of rays in all fins was completely revealed.

• Development and Reproduction
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• v.18 no.4
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• pp.259-266
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• 2014

The egg development and early life history of Korean spotted sleeper, Odontobutis interrupta which is Korean endemic species from Sora-choen was investigated. The Korean spotted sleeper were caught at Sora-myeon, Yeosu-si, Jeollanamdo, from Korea at May in 2014. The fertilized eggs were $4.23{\pm}0.05mm$ in long diameter and had oil globules. Hatching time of the embryo began about 442 hr 14 min after fertilization under water temperature of $19.5^{\circ}C$. The newly hatched larvae were $4.27{\pm}0.35mm$ in total length and their anus were not yet opened. 3 days after hatching postlarvae was measured $6.20{\pm}0.11mm$ in total length. 10 days after hatching postlarvae was measured $6.69{\pm}0.14mm$ in total length.

• Korean Journal of Animal Reproduction
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• v.16 no.2
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• pp.157-164
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• 1992

This stduy was carried out to obtain basic information available on ovulation, spawning, fertilization rate, hatching rate, and deformity rate after hCG injection in cyprinid loach, Misgurnus mizolepis. The results obtained in these experiments were as follows: 1. Ovulation and spawning occurred simultaneously and spawing was completed within 1 hour after ovulation. 2. More than 80% of fertilization rates appeared within 12 hours at 21$^{\circ}C$, 8 hours at $25^{\circ}C$, and 4 hours at 29$^{\circ}C$, respectively, following the onset of spawing. Afterwards, the fertilization rates of released eggs sharply decreased in three different water temperatures. 3. More than 70% of hatching rates appeared within 8 hours at 21$^{\circ}C$, 6 hours at $25^{\circ}C$, and 2 hours at 29$^{\circ}C$, respectively, following the onset of spawing. Afterwards, hatching rates of spawned eggs abruptly decreased in three different water temperatures. 4. The deformity rates of hatched larvae were high at $25^{\circ}C$, 8 hours following the onset of spawing. 5. Based on the developmental ability of oocytes, the optimum time of fertilization was 4 hours (stage 5) following the onset of spawing.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.5
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• pp.676-683
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• 2023

The development of the egg, larvae, and juveniles of Acheilognathus macropterus from the Wicheon stream of Nakdonggang River was investigated for early life history characteristics. The fish used in the study were collected from Wicheon stream located in Bian-myeon, Uiseong-gun, Gyeongsangbuk-do. The fertilized egg was 1.88±0.09 mm (n=30) in long diameter and 1.34±0.06 mm (n=30) in short diameter. After fertilization at a water temperature of 20℃, the egg took 31 h and 40 min to hatch. Newly hatched larvae had an average total length of 3.92±0.13 mm (n=30) and possessed a yolk sac the mouth and anus were not developed. Twenty days after hatching, the postflexion larvae had an average total length of 8.08±0.29 mm (n=30), with the tail tip fully bent at 45° and began feeding. Thirty-three days after hatching, the number of fin stems reached an integer with an average total length of 15.0±1.08 mm (n=30). In this study, differences in the egg size, hatching time, melanophore development period, and distribution location were confirmed between A. macropterus and allied species.