• Journal of Aquaculture
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• v.10 no.1
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• pp.25-32
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• 1997

Develoment precess and characteristics of eggs of the geoduck clam, Panope japonica are reporting in this study. Eggs and sperm were excised from gonad, artificially fertilized in an aquarium, reared under various temperature regimes, and record and record the larval period and the time need to reach a certain larval stage from ferilization. Unfertilized eggs of P. japonica appeared to be oval with a mean diameter of $70\mu$m and they became spherical after fertilization. The eggs of P. japonica can be classified as demersal. At a constant water temperature of $ 11^{citc}C$, it took 4 hours form fertilization to become four-cell stage, two days to become trochophore larvae, three days to become D-shape larvae, twenty-three days to become umbo stage, and thirty-six days to become fully grown veliger ready form settlement. A negative correlation was observed between the water temperature and the larval period of P. japonica. From fertilization to D-shape larvae, it took five days at 8$^{\circ}C$, while it was only two days to become D-shape larvae at $ 17^{citc}C$. Time required to D-shape larvae from fertilization was proportional to temperature, and the relationships were expressed as follows : To 8-cell stage, 1/t=0.0209 w-0.1167 (r=0.9967) To blastula stage, 1/t=0, 0055 w-0.0192 (r=0.9825) To trochophore stage, 1/t=0.0034 w-0.0155 (r=0.9907) To D-shape larvae stage, 1/t=0.0014 w-0.0023 (r=0.9843) (t, time in hours ; w, water temperature) Bioligical minimum temperature for egg development was calculated as 3.82$^{\circ}C$ in average.

• Journal of fish pathology
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• v.17 no.1
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• pp.67-74
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• 2004

This study investigates the influence of waterborne ammonia and nitrite on the zoea and megalopa stage larvae of tiger crab, Orithyia sinica under laboratory condition, focusing on the effects on survival and growth as deleterious responses of toxicant. Survival rate of zoea stage larvae exposed to control levels, and to 5, 10, 20 and 50 mg/L total ammonia-N, using a continuous flow system for 20 days was 80, 77, 45, 40 and 37%, respectively. Growth rate of zoea stage larvae exposed to 20 and 50 mg/L total ammonia was significantly lower than in controls after 20 days (P< 0.05). Survival rate and growth rate of megalopa stage larvae exposed to ammonia also decreased at greater than 10 and 50 mg/L, respectively. In the nitrite exposure experiment with zoea and megalopa stage larvae of tiger crab, survival rate was decreased in a concentration and exposure period-dependent way. The growth rate of zoea and megalopa stage larvae of tiger crab exposed to nitrite decreased at greater than 150 mg/L nitrite concentration.

• Parasites, Hosts and Diseases
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• v.23 no.2
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• pp.247-252
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• 1985

In the present study, the effect of primary infection to reinfection with Ascaris suum larvae was experimented in mouse model. Mice were challenged with 1,000 infective stage eggs of Ascaris suum. The embryonated eggs were directly introduced into stomach of mice. Reinfection was performed at 50 days after the primary infection with same method as primary infection. Mice were sacrificed 3, 5, 7, 10, 15 and 20 days after infection in both groups respectively. Larvae collected from livers and lungs with Baermann's apparatus were enumerated and measured after sacrifice. Sera of mice were also collected at same time. The results of the experiment were as follows: With antigen prepared from coelomic fluid of adult Ascaris suum and sera collected from mice before reinfection, the production of antibody in experimental mice was confirmed by the gel-diffusion technique. In the livers of reinfected mice, the larvae were recovered up to 10 days after challenge, otherwhile in the primary infected mice, the larvae were observed up to 7 days. The maximum number of larvae were observed in the lungs of primary infected mice on 10 days after inoculation. In the lungs of reinfected mice, maximum number of larvae were recovered on 7 days after, only few larvae were recovered on 10 days after reinfection. As regards the growth of the larvae, the third stage larvae, over $500{\mu\textrm{m}}$ in length, appeared in livers at 5 days after reinfection, but it couldn't be found on 7 days and 10 days after challenge. The third stage larvae continuously developed were observed in lungs of mice from 5 days after reinfection. In conclusion, it was found that development of larvae in livers of immune mice were probably repressed by the immune mechanisms being rises in livers and defence mechanism is also acting by interfering with the process of larval penetration into the lung from the liver.

• Journal of Aquaculture
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• v.17 no.3
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• pp.221-227
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• 2004

In the present study, we investigated the effects of food and salinity on growth and survival of river puffer, Takifugu obscurus offsprings in indoor land-based tank during the early development. In the food experiment, the river puffer larvae (TL 8.7$\pm$0.1 mm, BW 20.0$\pm$3.2 mg) were fed with tubificid, Limnodrilus gotoi, water flea, Daphnia carinata, mysid, Neomysis awatschensis, Manila clam, Ruditapes philippinarum and artificial food together Artemia nauplii for 30 days, and the growth and the survival of larvae were investigated. In the salinity experiment, the river puffer larvae and juvenile at three stages (Stage I: TL 5.8$\pm$0.4 mm; Stage II: TL 12.0$\pm$0.2 mm, Stage III： TL 44.5$\pm$0.7 mm) were supplied with Artemia nauplii, water flea and/or artificial food and were reared in 0, 10, 20 and 30 psu at respective stages. The results shows that the growth rates of larvae feeding with artificial food and tubificid together Artemia nauplii were higher than those of larvae in other groups, but the survival rates of larvae feeding with water flea and mysid together Artemia nauplii were higher than those of larvae in other groups. In salinity, the results shows that the growth and survival rates of offsprings were significantly higher in 10∼20 psu than those in 0 and 30 psu at Stage I and n. At Stage III, the growth and the survival rates were the highest in 20 psu, but the lowest in 0 psu. However, it should be noted that the rates in 0 and 30 psu were significantly enhanced at Stage III in comparison with those at Stage I and II. Therefore, it is concluded that river puffer, T. obscurus is euryhaline marine species, which can normally grow and live at salinities from 0 to 30 psu, and that a combinative supplement with Artemia nauplii and water flea, D. carinata may confer an advantage on growth and survival of the river puffer offsprings in indoor land-based tank.

• Journal of Life Science
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• v.14 no.2
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• pp.235-238
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• 2004

The possibility for developing multistage culture system to cultivate larvae by computer simulation with basic experiments was investigated. This culture system was composed of 3 stages. At the 1st stage, Chlorella sp. were cultivated and at 2nd stage Chlorella sp. were supplied to rotifer (Brachionus plicatilis), and rotifer were supplied to larvae at the 3rd stage. In this study, Chlorella sp. were cultivated by batch culture to search for the possibility of continuous feeding to rotifer at 2 nd stage. The maximum specific growth rate ($\mu$$_{max}$) of Chlorella sp. at the logarithmic phase was 0.56 [1/day]. Rotifer was cultivated by fed-batch culture at the feeding rate of Chlorella sp., $10^3$, $10^4$, $10^{5}$ and $10^{6}$ [cells/rotiferㆍh] to search for the relation between the feeding rate of Chlorella sp. and the growth rate of rotifer. As the results, the minimum feeding rate of Chlorella sp. was 2.8 ${\times}$ $10^4$ [cells/rotiferㆍday] in the multistage culture system, then the change of rotifer concentration at 2nd stage was simulated by computer. The required amount of rotifer for the growth of larvae was also increased as the growth of larvae. On the 9th day of the culture, the rotifer uptake rate of larvae was 250 [cells/rotiferㆍday]. Based on these basic experiments and results, It was suggested that the possibility of multistage culture system to cultivate larvae with continuous feeding of Chlorella sp. and rotifer.r.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.93-94
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• 2003

To investigate the food organisms of the Acentrogobius elongata during the juveniles stage, the stomach contents of fish, captured in the intertidal zone of Chungchongnam-do Sochon-gun Su-myon Dodun-ri between on early in June from the end of May 2000, were observed. Total length of the fingerings of A. elongata was 1.0~3.0cm size, and the participation rate of feeding was 68.6%. Main food organisms were such as copepods, shrimp larvae, polychaete larvae, and these occupied more than dry weight 4%. Copepods among them dominated the most quantitys by average 64.6%, and food organismsms appeared by order of polychaete larvae and shrimp larvae etc.. Therefore, most important food organisms of fingerlings stage of A. elongata were copepods, polychaete larvae, shrimp larvae etc.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2002.05a
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• pp.359-360
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• 2002

To investigate the food organisms of the Tridentiger trigonocephalus during the juveniles stage, the stomach contents of fish, captured in the intertidal zone of Chungchongnam-do Sochon-gun Su-myon Dodun-ri between on early June from end if may 1999, were observed. Total length of the juveniles of T. trigonocephalus was 5.5mm∼9.0mm size, and the participation rate of feeding was 68.5%. Main food organisms were such as copepods, amphipods, shrimp larvae, polychaete larvae, and these occupied more than dry weight 2%. Copepods among them dominated the most quantitys by average 67.5%, and next, food organismsms appeared much by order of polychaete larvae and shrimp larvae etc.. Therefore, most important food organisms of juvenile stage of T. trigonocephalus were copepods, polychaete larvae, shrimp larvae etc.

• Proceedings of the Korean Aquaculture Society Conference
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• 2002.08a
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• pp.225-226
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• 2002

To investigate the food organisms of the Tridentiger trigonocephalus during the juveniles stage, the stomach contents of fish, captured in the intertidal zone of Chungchongnam-do Sochon-gun Su-myon Dodun-ri getween on early June from end of May 1999, were observed. Total length of the juveniles of T. trigonocephalus was 5.5mm∼9.0mm size, and the participation rate of feeding was 68.5%. Main food organisms were such as copepods, shrimp larvae, polychaete larvae, and these occupied more than dry weight 2%. Copepods among them dominated the most quantitys by average 67.5%, and next, food organismsms appeared much by order of polychaete larvae and shrimp larvae etc.. Therefore, most important food organisms of juvenile stage of T. trigonocephalus were copepods, polychaete larvae, shrimp larvae etc.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.565-566
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• 2001

To investigate the food organisms of the Chasmichthys dolichognathus during the juveniles stage, the stomach contents of fish, captured in the intertidal zone of Chungchongnam-do Sochon-gun Su-myon Dodun-ri between on early June from end of May 1998, were observed. Total length of the juveniles of C. dolichognathus was 6.5mm ∼10.0mm size, and the participation rate of feeding was 67.7％. Main food organisms were such as copepods, amphipods, shrimp larvae, polychaete larvae, and these occupied more than dry weight 2％. Copepods among them dominated the most quantitys by avergage 65.5％, and next, food organismsms appeared much by order of polychaete larvae and shrimp larvae etc. Therefore, most important food organisms of juvenile stage of C. dolichognathus were copepods, polychaete larvae, shrimp larvae etc.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.1
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• pp.23-29
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• 2022

This study was carried out to clarify the egg, larvae and juveniles development of Misgurnus anguillicaudatus, and relationships of M. anguillicaudatus and M. mizolepis, Cobitididae Fishes. The adult fishes were collected in Samsan-cheon, Haenam-gun, Jeollanam-do, Korea and their spawning inducement was carried by ovaprim injections. The egg shape was circular and the size was average 1.12 mm. The eggs were hatched at 61 to 72 h after fertilization. The newly hatched larvae had an average 3.23 mm in total length (TL). At 5 days after hatching, the larvae reached to post larval stage and they were 10.3 mm in TL. At 19 days after hatching, it reached to juvenile stage and was 25.3 mm in TL. The egg size of M. anguillicaudatus was almost same as M. mizolepis but the hatching period of M. anguillicaudatus has taken longer. It was possible for interspecific distinguishability of M. anguillicaudatus and M. mizolepis when their larvae reached to juvenile stage by the development of keel-like ridges.