• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.2
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• pp.170-177
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• 2018

Samples were obtained from broodstork in May, 1998, while naturally fertilized embryos were maintained and the process of skeletal development was observed from larvae and juveniles. Prelarvae immediately after hatching showed an average total length of $5.38{\pm}0.41mm$ (n=10), premaxillary and dentary were ossified, parasphenoid was ossified in the cranium, and centrum and caudal bone did not ossify. Prelarvae showed ossification with maxillary, articular and epihyal and branchiostegal rays of hyoid arch were ossified at 5 days after hatching with an average total length of $6.40{\pm}0.39mm$ (n=10). The vertebrae began to ossify in the direction of the tail, and neural spine began to ossify above the ossified vertebra. Postlarvae showed ossification of lateral ethmoid, parietal, and caudal skeleton in the cranium when the average total length was $7.30{\pm}0.12mm$ (n=10) in 8 days after hatching. At 22 days after hatching, postlarvae ossified maxillary in the cranium, and ossified endopterygoid and ectopterygoid, etc. in the palate, when the average length of $11.1{\pm}1.27mm$ (n=10). At 32 days after hatching, with the average length was $12.8{\pm}1.97mm$ (n=10), caudal skeleton had one additional epural bone ossification, resulting in ossification of a total of 3 epural bone to complete ossification of all spicules.

• Development and Reproduction
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• v.18 no.1
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• pp.13-23
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• 2014

This study is conducted to monitor the morphological developmental features of the egg development, larvae and juvenile of Epinephelus septemfasciatus, the fertilized eggs were gotton using artificial insemination. Matured parents are collected from marine caged fish farms in Geomun-ri, Samsan-myeon, Yeosu-si, Jeollanamdo Korea in June 2012. The fertilized eggs were pelagic eggs containing one oil globule, and measured 0.81~0.89 mm ($0.85{\pm}0.04mm$, n=50) in diameter. In regard to rearing environment, the water temperature is $21.0{\sim}23.0^{\circ}C$ and the salinity is 32.0~33.2‰. Hatching was observed from 48 hours after fertilization, the mouth and anus of prelarvae was not opened but had egg yolk at newly hatched. 4 days after hatching, the mouth and anus of postlarvae was opened and began to eat Rotifer and was measured 2.40~2.49 mm ($2.45{\pm}0.03mm$ n=10) in total length. 12 days after hatching, postlarvae was measured 3.77~4.67 mm ($4.27{\pm}0.33mm$) in total length, its the second pole tide of dorsal fin and the first pole tide of pelvic fin was extended longitudinally. 71 days after hatching, juvenile was measured 40.5~45.4 mm ($42.6{\pm}2.04mm$) in total length. Seven bands were observed in body, and pole tides of dorsal and pelvic fins were shortened.

• Journal of Microbiology and Biotechnology
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• v.21 no.11
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• pp.1109-1115
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• 2011

A highly sensitive and specific TaqMan real-time PCR was used to quantify hepatopancreatic parvovirus (HPV) type III infections in wild broodstocks and hatchery-reared postlarvae (PL) of Fenneropenaeus chinensis. Totals of 159 and 162 wild brooders from three locations were captured, and 140 and 180 PL were obtained from seven and six commercial hatcheries in 2007 and 2008, respectively. Among the three wild broodstock groups from 2007, only 1 group showed HPV infection and 3.2% of 159 brooders were positive for HPV infection. In 2008, HPV infections were observed from all three wild broodstock groups with $1.93{\times}10^4$ copies/mg tissue of pleopods. Of 162 brooders, 26.6% were positive for HPV infection. No PL from the two hatcheries collected in 2007 showed HPV infection, and PL from the rest of the five hatcheries had up to $1.74{\times}10^6$ copies/ng of DNA, and PL from three hatcheries showed HPV infections with over 1,000 copies/ng of DNA. The PL from all seven hatcheries collected in 2008 showed up to $2.10{\times}10^5$ HPV copies/ng of DNA. PL from two hatcheries showed less than 100 copies/ng of DNA, but PL from the rest of the hatcheries showed HPV infections with over 1,000 copies/ng of DNA. These results show that HPV type III is widely distributed in Korea in addition to previously reported HPV type I, and they can be effectively detected by type-specific realtime PCR.

• Korean Journal of Ichthyology
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• v.35 no.1
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• pp.1-9
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• 2023

The morphological development of larvae and juvenile of Sebastes taczanowskii were studied. The S. taczanowskii were caught at Goseong-gun, Gangwon-do from March in 2016. Larvae beared at water temperature of 11~12℃ (mean 11.5±0.5℃). The just beared larvae were 5.25~5.96 mm (mean 5.60±0.19 mm, n=30) in total length and their mouth and anus were already opened. They began to eat rotifer and transformed to postlarvae stage. 35 days after bearing postlarvae was measured 7.16~11.4 mm (mean 9.02±1.00 mm) in total length and the tip of notochord was bent upward. 48 days after bearing juvenile was measured 9.45~18.7 mm (mean 14.4±1.75 mm) in total length with dorsal fin rays XIII, 13~15; anal fin rays III, 6~8; caudal fin rays 16.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.3
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• pp.247-252
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• 1995

To investigate the food organisms of the Japanese anchovy (Engraulis japonicus) during the first feeding stage, the gut contents of anchovy, captured in Kwangyang Bay at June 1990, were observed. Anchovies started to eat from 3.0mm (NL) after finishing to absorb the yolk. The food organisms were composed of copepod eggs and nauplii tintinnids, and etc. The major food organisms of the anchovy larvae of 3.0-3.8mm (NL) were copepod eggs and nauplii, whereas those of larvae longer than 3.8mm(NL) were only copepod nauplii.

• Korean Journal of Ichthyology
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• v.17 no.1
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• pp.29-35
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• 2005

Fertilized eggs of Takifugu pardalis (Temminck et Schlegel) were collected on the coast of Jook-do in Tongyong, Korea, from March 1997 to June 1999, and hatched and reared in the laboratory to investigate osteological development of the larve and juveniles. The newly hatched larvae attained a mean of $3.13{\pm}0.05mm$ in total length (TL). Ossification first began in the parasphenoid, premaxillary and dentary. At 5 days after hatching, the postlarvae attained a mean of $3.82{\pm}0.03mm$ in TL, and their sphenotic, prefrontal, preopercle, opercle, maxillary, and articular were ossified. At 15 days, the postlarvae attained a mean of $7.84{\pm}0.06mm$ in TL, their nasal and posttemporal bones were ossified and the hyoid arch completed ossification. Ossification of all bones was completed in the juveniles (mean = $10.21{\pm}0.06mm$ in TL) at 21 days.

• Korean Journal of Ichthyology
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• v.27 no.1
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• pp.1-9
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• 2015

The morphological and skeletal development and larvae and juvenile of Sebastes koreanus were studied. The Sebastes koreanus were caught at Yeosu-si, Jeolla-namdo from March in 2014. Larvae beared at water temperature of $13.5{\sim}15.5^{\circ}C$ (mean $14.5{\pm}0.1^{\circ}C$). The just beared larvae were 6.38~6.43mm(mean $6.40{\pm}0.02mm$, n=5) in total length and their mouth and anus were already opened. They began to eat rotifer and transformed to postlarva stage. 5 days after bearing postlarvae was measured 6.45~6.49 mm (mean $6.47{\pm}0.02mm$) in total length. 15 days after bearing postlarvae was measured 6.55~6.72mm(mean $6.64{\pm}0.08mm$) in total length. 60 days after bearing juvenile was measured 15.5~20.0 mm (mean $17.7{\pm}2.25mm$) in total length with dorsal fin rays X IV-12~13; anal fin rays III-7; caudal fin rays 16.

• Korean Journal of Environmental Biology
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• v.35 no.1
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• pp.6-12
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• 2017

This study focused on the physiological change of the shrimp, Litopenaeus vannamei postlarvae 15 stages, under different acclimation methods up to the endpoint of 4 practical salinity unit (psu). Besides using sea water as the control, two acclimation methods, fast acclimation (50% salinity reduction every 8 hours) and slow acclimation (50% salinity reduction every day), were adapted. Results show that the survival rate, glucose and blood uric nitrogen of each group were not significantly different. However, the ion profile differed according to the acclimation methods. Magnesium and sodium of shrimps acclimated to low salinity in both the methods, showed lower concentration than shrimps at 32 psu sea water. Especially, $Na^+$ concentration, which directly influences the osmolality of shrimp, decreased sharply in the fast acclimated group during the first eight hours (from 32 psu to 16 psu). To reduce acclimation stress, it is recommended to take more than eight hours during the first step for reducing the salinity.

• Journal of Aquaculture
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• v.1 no.1
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• pp.1-11
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• 1988

There are many problems to be solved for the establishment of more feasible and simplified method of seed production of marine fishes. One of the most important tasks in seed production is to clarify the feeding ecology of larvae and juveniles under. rearing conditions. In the present study, two groups of postlarvae-juveniles of the flounder, Paralichthys olivaceus were used. One ranging 11.38 to 17.08 mm in mean total length was fed with Artemia nauplii at two different water temperatures (19 to $21^{\circ}C$ and 24 to $25^{\circ}C$) and the other ranging 4.39 to 10.64 cm in mean total length was fed with prepared diet. Time required from the start of feeding to satiation was 45 to 55 minutes at 24 to $25^{\circ}C$ and nearly one hour at 19 to $21^{\circ}C$. Mean numbers of Artemia nauplii in digestive tract were 236 to 375 individuals per fish at 24 to $25^{\circ}C$. The amount of food remained in the intestine was $24.8\%$ of the total food in the digestive tract. In juveniles of 4.39 to 10.64 cm in mean total length, amount of prepared diet consumed at satiation was 0.04 to 0.46 g per fish. Digestive tract index in juveniles was rapidly decreased for 24 hours after satiation and kept nearly constant after 48 hours, showing that the time to completely digest the prepared diet in juveniles was estimated to be about 48 hours.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.4
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• pp.401-409
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• 1983

The distribution of anchovy eggs and larvae was studied using the ichthyoplankton samples and oceanographic data collected in the western and southern waters of Korea over the period of April through June in 1981 and 1982. Three water masses, the Tsushima Warm Current, the South Korean Coatal Water and the Yellow Sea Bottom Cold Water, are found to exert extensive influences of the distribution of anchovy eggs and larvae. The Tsushima Warm Current contacts with the South Korean Coastal Water to produce a coastal front between Cheju Island and Tsushima Island in the southern waters of Korea. Off the west coast of Korea, a coastal front is also formed running parallel with the western coast-line of Korea in the area between the Yellow Sea Bottom Cold Water and the extended part of the South Korean Coastal Water. In the southern waters of Korea anchovy eggs were found chiefly in the coastal waters inside the front, and larvae appeared to both sides on the front. The distribution of anchovy eggs and larvae off the west coast of Korea, however, was limited largely to the coastal waters of more than $12^{\circ}C$ in temperature. In the southern waters of Korea prelarvae appeared in the coastal area, and postlarvae in the offshore area. While in the western waters of Korea prelarvae were found in the southern part of the waters, and postlarvae in the northern part. Anchovy eggs and larvae were distributed in the considerably limited area of the coastal waters off the south coast of Korea in 1981 when the temperature gradient of the coastal front was sharper than in 1982.