• Korean Journal of Ichthyology
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• v.29 no.4
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• pp.261-266
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• 2017

Microphysogobio koreensis is an endemic Korean freshwater fish that is protected as an endangered fish by the Ministry of Environment in Korea. In this study, we attempted to investigate the spawning period and spawning characteristics of M. koreensis to obtain basic information for its conservation. Though natural and histological observation, the spawning season occurred between April and May, with peak spawning occurred in early May when the water temperature was $20{\sim}23^{\circ}C$. During the spawning season, males had a bright-orange body and a thick red horizontal line from the rear of the operculum to the caudal peduncle, along with a lateral line, while females had a dark brown body. Nuptial organ had not appeared. The number of eggs in the ovaries was 10,705~22,165 ($15,573{\pm}4,274$). The number and appearance ratio of mature eggs were 1,100~5,920 ($3,383{\pm}2,126$) and 10.3~44.8% ($22.4{\pm}15.6$), respectively. And the size of mature eggs was 0.60~1.00 mm ($0.74{\pm}0.06$).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.4
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• pp.308-316
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• 1987

The flying fish, Prognichthys agoo, is widely distributed in the coastal waters of south-eastern Korea. On July 14, 1986, mature adults of flying fish were captured from U-do, Cheju-do. The eggs were stripped and fertilized by the wet method on the ship. The mature eggs are demersal and adhesive with 30-40 filaments. The egg diameter varied from 1.42 to 1.58 mm. The water temperature throughout incubation ranged from 23.70 to $27.82^{\circ}C$, and salinity was maintained at $30.75-33.76\%_{\circ}$. The hatching took place in 174 hours after fertilization. The newly hatched larvae measured 4.75-5.25 mm in total length possessing yolk sac and about 45-46 myotomes. The larvae cultured for ten days after hatching reached 11.45-12.60 mm in total length and entered the juvenile period of life. Twenty days after hatching, the juveniles measured 20.01 mm in mean total length, and the scales were formed behind the pectoral fin.

• Korean Journal of Community Nutrition
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• v.19 no.4
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• pp.361-371
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• 2014

Objectives: This study was performed to set easily applicable portion sizes by sex and age for children at the Community Child Centers (CCC) in Korea. Methods: Considering the age and gender specific energy level at Target Patterns for children aged 6-18 years, which were suggested as a part of the 2010 Korean Food Guidance System (KFGS), we set three meal sizes. We reclassified the recommended daily servings of Grains, Meat fish eggs beans and Vegetables group at Target Patterns into three meal sizes, and then calculated the recommended serving per meal. Each proposed amount of food per meal was calculated based on serving size of foods commonly eaten at KFGS, which was then allocated to five meal components; rice, soup stew, protein and vegetable side-dishes and Kimchi. Each proposed amount of food per meal was applied to 173 menus' recipes from CANpro 3.0 as main ingredient's amounts. We cooked the 173 menus at the medium size and measured their weights after cooking. Results: Each recommended serving per meal was 0.75, 0.9 and 1.2 for Grains; 1.2, 1.6 and 2.4 for Meat fish eggs beans; 2, 2.4 and 2.8 for Vegetables by meal sizes. Among five meal components, the ratio of small and large to medium size was 1/5 less and 1/3 more for rice and 1/3 less and 1/3 more for soup stew, protein side-dish and Kimchi, respectively. We suggested the same amount for a vegetable side-dish to encourage vegetable intake. Proper portion sizes per meal of medium were rice 190 g, soup stew 210 g (solid ingredients 60 g), protein side-dish 100 g (meat eggs beans) and 70 g (fish), vegetable side-dish 80g and Kimchi 30 g. Conclusions: Proper portion size per meal suggested in this study may be useful at the CCC where dietitians are not available and the approach could be applicable to the other types of meal services.

• Journal of Aquaculture
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• v.11 no.2
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• pp.141-149
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• 1998

Spawning inducement of striped knife-jaw, Oplegnathus fasciathus, was attempted by two experiments. In experiment I (Exp. I), water temperature was gradually increased from 14.5$^{\circ}C$ in December 15, 1996 to $21.0^{\circ}C.$ in February 22, `997 and then maintained at this level. Photo-period was also gradually increased from 10.5L/13.5D in December 15, 1996 to 15.5L/8.5D in February 17, 1997, and then maintained at this level. In experiment II (Exp. II), water temperature was increased in the same way from Exp. I. Photoperiod was natural conditions from December 1996 to March 9, 1997, and then suddenly increased to 15.5L/8.5D until the end of experimental period. Spawning of the fish was occurred from February 22 through April 2, 1997 (for 40 days) in Exp. I. Number of total spawned eggs was 30.04 million and fertilization rate was 77.2%. The fish began to spawn at $21.0^{\circ}C.$ and 15.5L/8.5D. It requied 65 days to spawn since the water temperature had increased from $14.5^{\circ}C.$ to $21.0^{\circ}C.$. Spawning of the fish was not occurred until March 9, 1997 in Exp. II. After 7 days, photo-period was suddenly incresed to 15.5L/8.5D and fish were spawned from March 17 through April 4, 1997 (for 20 days). Number of total spawned eggs was 21.28 million and fertilization rate was 72.1%. The fish began to spawn at $21.0^{\circ}C$ and 15.5L/8.5D. It required 65 days to spawning since the water temperature had increased from $14.5^{\circ}C$ to $21.0^{\circ}C$.

• Korean Journal of Ichthyology
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• v.28 no.4
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• pp.215-222
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• 2016

Triploidy was induced in the marine medaka, Oryzias dancena by cold shock treatment ($0^{\circ}C$) of fertilized eggs for 30, 45, or 60 min, applied two minutes after fertilization. The triploid genotype was induced by each of the thermal shock regimes tested. The best result was obtained when the eggs were treated for 45 min, which induced triploidy in all the resulting fish. Triploidy was confirmed using chromosomal and flow cytometer analyses, and erythrocyte measurements. The surface areas and volumes of the erythrocytes of triploid fish were significantly larger than those of diploid fish, and their chromosome number (3N=72) was 1.5 times greater that for the diploids (2N=48). Based on a flow cytometer analysis, the triploid fish had approximately 1.5 times the cellular DNA content (2.40 pg/cell) of the diploid specimens (1.61 pg/cell). Data from this study provide the basis for the development of unique models for studying reproductive confinement in transgenic fish.

• Development and Reproduction
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• v.13 no.2
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• pp.123-132
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• 2009

The gonadosomatic index (GSI), fatness, ovarian development, first sexual maturity, and fecundity of the Korean anchovy Coilia nasus were investigated by histological observations and morphometric analysis from January to December, 2007. The GSI and fatness began to increase in February, and reached the maximum in June when the ovary was getting mature and spawning occurred. Thereafter these parametes rapidly decreased in July when spawning occurred. Therefore, monthly changes in the GSI and fatness were closely related to ovarian maturation and spawning. The duration of ovarian development in females can be classified into five successive stages: early growing stage (February to March), late growing stage (March to April), mature stage (May to June), ripe and spent stage (June to July), and recovery and resting stage (December to January). Maturation and spawning of this species occurred between June and July during the period of high seawater temperature-long day length. Percentages of first sexual maturity in female individuals were over 50% for fish ranging 24.1 to 27.0 cm in total length, and 100% for fish over 30.1 cm in total length. The number of total eggs and mature eggs in the absolute fecundity were increased with the increase of total length and body weight, respectively. The number of total eggs and mature eggs in relative fecundity were also proportional to total length, but rather these numbers decreased in the maximum body weight (126.0${\sim}$150.0 g).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.6
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• pp.536-542
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• 1984

Fish eggs and larvae in the western waters of Korea are surveyed during the periods from February to August in 1982. Six species of eggs and forty-two species of larvae are occurred in the survey area. The dominant species occurred during the study periods are Ammodytes personatus, Enedrias sp., Engraulis japonica, Callionymus sp., Gobiidae, etc. Major spawning month and ground of each species are estimated from the data, i.e., occurrence month and abundance of eggs and larvae by survey month and area, as well as the optimum water temperature and salinity for spawning.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.1
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• pp.16-23
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• 1987

The cyprinid loach, Misgurnus mizolepis $G\ddot{u}nther$, a freshwater teleost, is a member of the family Cobitidae and is known to distribute in Korea and China. This fish is considered to be an excellent food fish in Korea. This report is a description of the gross morphology of the embryos and larvae up to the development of juvenile period of life. The eggs were obtained by injecting gonadotropin and fertilized by wet method in the laboratory on July 10 in 1986. The inseminated eggs were rinsed with tap water and incubated at $25^{\circ}C$. Live, freshly laid eggs were separative, demersal, adhesive, light yellow and average 1.1mm in diameter. The hatching took place in about yellow and average 1.1mm in diameter. The hatching took place in about 24 hours after fertilization. The newly hatched larvae were average 2.7 mm in total length possessing yolk sac and 35-36 myotomes. Ten hours after hatching, the prelarvae attained 3.5 mm in total length. The first heart pulse and melanophores at the side of the body were observed at this stage. Yolk sac was completely reserved at four days after hatching. The larvae that was cultured 24 days after hatching, 15.4-16.4 mm in total length, entered the juvenile period of life. All the un rays were already peresent; D. III 6, A. III, 5, P.10, V. 4-5, C.14.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.5
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• pp.477-483
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• 1985

This paper describes seasonal changes of total length, hepatosomatic index (HSI), fatness, egg-diameter composition, and fecundity of the longchin goby Chasmichthys dolichognathus(HILGENDORF). The specimens used were captured in the tide pool of Tongbaekseom, Pusan, Korea from February 1983 to January 1984. The age of longchin goby, tested by size frequency, was believed to be usually one year which grows to 8.0 cm in total length. The annual variations of HSI reached the maximum in the early spring when the gonad was actively growing and decreased during the spawning season from April to July. The coefficients of fatness were represented low values for the spawning periods. Frequency distribution of the egg diameter of mature ovary has three modes: one is the evident mode of the ripe eggs group, and the other two are modes of maturing and immature eggs groups. And an individual is considered as spawns one in the spawning season. Relationships between the fish size in total length (TL cm) and the number of ovarian eggs(F), the fish weight (BW g) and the number of ovarian eggs are indicated by the exponential equation respectively : F=42.585 $TL^{1.608}$, F= 524.589 $BW^{0.475}$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.5
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• pp.721-726
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• 1998

The changes of thyroid hormone levels in plasma, eggs and yolk-sac larvae in female rockfish (Sebastes schiegeli) were examined after maternal injection of 3,5,3'-triiodo-L-thyronine ($T_3$) with a dose of 20 mg/kg fish wt. There were no differences of L-thyronine ($T_4$) level in maternal plasma and yolk-sac larvae between $T_3$ injection and vehicle-injected control. The significant decrease of $T_4$ level was found in eggs from the $T_3$ injected mother fish compared with that of control. $T_3$ levels in maternal plasma, eggs, and yolk-sac larvae were significantly elevated by $T_3$ injection. Therefore $T_4$ and $T_3$ in maternal circulation may be transferred into oocytes and subsequently into the yolk-sac larvae. These findings suggest that thyroid hormones may play some roles on physiological metabolism during early larval development of rockfish.