• Korean Journal of Ichthyology
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• v.1 no.1_2
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• pp.73-82
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• 1989

The development of eggs and larvae, and minute scale-like tubercles on the skin surface of the larval Acanthorthodeus asmussi from Korea were observed in the laboratory. The egg was nearly ovoid-shaped. The number of egg averaged 195 per an oviposition. The morphological character of larval development was relatively similar to those of Acheilognathus tabira tabira, A. tabira subsp. (a), A. yamatsutae, A. moriokae, A. cyanostigma and A. rhombeus. The larvae of this species had many scale-like tubercles ellipsoided in a diagonal cross section on the skin surface of the body. And also this species moved like incessant wiggly movement pattern as that of fly maggot duing the larval development. As regards the tubercles and larval movement pattern, the larvae of A. asmussi shared similar characters with those of Acheilognathus rhombeus, A. longipinnis and Pseudoperilampus typos. Hence A. asmussi may be closely related to these species. The latter three species are autumn-spawning bitterlings and the larval development always retard in a certain stage, while A. asmussi is a spring-summer spawning species and the larval development never retards. Judging from these facts, it should be considered that there are close relations in evolutionary trend between the two spawning species.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.6
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• pp.509-519
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• 1987

Annual reproductive cycle of the Damselfish, Chromis notatus collected monthly at the four coastal areas around Chejudo, Korea are studied on the bases of histological observations of gonadal tissue and various quantitative variables including gonadosomatic index (GSI), fatness, egg diameter composition and the first maturity. The ovary consisted of a pair of saccular structure with many ovarian sacs. Oogonia proliferated along the germinal epithelium of the ovarian sac. Young oocytes with basophilic cytoplasm showed several nucleoli along the nuclear membrane. When the oocytes reached about $450{\mu}m$ in diameter, nucleus migrate toward the animal pole, nuclear membrane disappeared and most of cytoplasm were filled with yolk materials and oil drops. After ovulation, residual follicle and growing oocytes remaining in the ovarian sacs degenerated. But early young oocytes without follicle layer were not degenerated, and growing continuously till the next year. The testis consisted of a pair of lobular structures in the right and left were united in the posterior seminal vesicle. Cortex of testis was composed of many sperm ducts connected with lobuli. GSI began to increase from March, starting season of longer day length and higher water temperature, and reached the maximum value between June and August. It began to decrease from September with the lowest value appearing between October and February without any evident variation. The annual reproductive cycle could be devided into five successive stage : growing(April to Many), mature(May to August), ripe and spent (June to August) and recovery and resting stage(September to March). The spawning peak occurred from June to August. According to the frequency distribution of egg diameter, Chromis notatus was a polycyclic species to spawn twice or more in a spawning season. Fatness, correlated with gonadal phases, was remarkably decreased by spawning. Percentage of the first maturity . in femate and male fish ranging from 7.0 to 7.9 cm were $50\%$ and from 9.0 to 9.9 cm in total length $100\%$.

• Korean journal of applied entomology
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• v.59 no.2
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• pp.133-138
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• 2020

In 2016, the two-spotted cricket was approved as a general food ingredient by the Korean Ministry of Food and Drug Safety. Additionally, the two-spotted crickets have high protein content (60%) and can be reared throughout the year even during the overwintering period. In this study, storage conditions were set in case cricket breeding was not possible due to problems such as breeding space and labor costs, and selection oviposition mats to determine high fecundity rates and low cannibalism rates for the eggs were investigated. The oviposition mat was mostly composed of soil (p < 0.05). Less than 62 crickets per 10 litters were found to be best suited for 1 day of spawning, based on the cannibalism rate of the eggs during the egg laying period. The results from the hatched eggs indicated that the hatching extended 12 to 14 days, and the best hatching rate was approximately 85% when stored at low temperatures(16℃) for 10 days. An efficient production proposed method that established the best oviposition mat and egg storage method for the cricket.

• The Korean Journal of Malacology
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• v.28 no.1
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• pp.7-12
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• 2012

The effect of water temperature on spawning induction, larval development, spat settling and its growth of the cockle shell, Fulvia mutica, were investigated to obtain the basic data for effective seed production. The eggs, which were randomly divided into 6 groups of water temperatures of 14, 17, 20, 23, 26 and $29^{\circ}C$, were transferred into 1 L beaker, respectively. The relationships between the water temperature and the required time (1/h, hour) by each egg developmental stage were calculated. Biological minimum water temperature and the cumulative water temperature until egg development of the veliger stage were calculated to be $0.1^{\circ}C$ and $397.3^{\circ}C$, respectively. The optimal water temperature for developmental bioassay of F. mutica was clarified to be $23^{\circ}C$. The required time for the embryo to become veliger larvae was 20 hours at $23^{\circ}C$.

• Korean Journal of Ichthyology
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• v.33 no.3
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• pp.167-176
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• 2021

This study was carried out to clarify the egg, larvae and juveniles development of Abbottina springeri. For the experiments, the matured adults were collected at the Seowon-cheon, Dangjin-si, Chungcheongnam-do, in Korea. The amount of spawning of female A. springeri was about 1,225~2,100 (1,662±437, n=10). The fertilized eggs were circular in shape and 1.05~1.13 (1.08±0.02, n=30) mm in diameter. The hatching time was required 72 hours to 80 hours after fertilization under water temperature of 22℃. The newly hatched larvae were 2.10~2.23 (2.16±0.04, n=10) mm in total length and had egg yolk in the abdomen but the mouth was not opened. At 5 days after hatching, the preflexion larvae were 3.19~3.30 (3.24±0.03, n=10) mm in total length and the most of yolk-sac was absorbed. At the 15 days after hatching, the flexion larvae were 4.97~5.30 (5.13±0.12, n=10) mm in total length and the tip of the caudal fin was began to bend upward. At the 25 days after hatching, the postflexion larvae were 8.97~9.60 (9.44±0.16, n=10) mm in total length and the tip of the caudal fin was bent at 45°. At the 35 days after hatching, the juvenile were 12.0~13.5 (12.7±0.53, n=10) mm in total length and all fin-rays (iii7 dorsal fin, iii6 anal fin, i7 ventral fins) were reached a constant number of each part.

• Korean Journal of Ichthyology
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• v.36 no.1
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• pp.10-19
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• 2024

This study investigated the early life history of Hemibarbus labeo from in Wicheon, stream Nakdonggang-River, and compared their characteristics with closely related species. In April 2021, egg formation and development of autonomous fish were observed in fertilized eggs collected at four spawning sites. The size of the fertilized egg was 1.93~2.39 (average 2.22±0.15, n=30) mm. The water temperature was 22.2~24.1°C, and the hatching time took 109~115 hours. Newly after hatching, the total length of the yolk-sac larvae was 7.50~8.80 (average 7.99±0.46) mm, and the mouth and anus did not develop and had difficulty in being yolk. 6 days after hatching, the preflexion larvae were fed with a total length of 9.49~10.2 (9.78±0.23, n=30) mm. 10 days after hatching, the flexion larvae was 9.97~11.9 (10.7±0.72, n=30) mm in total length, and the tail of the vertebrae began to bend. 20 days after hatching, the postflexion larvae was 12.6~15.2 (13.9±0.77, n=30) mm in total length, and the tailbone was completely bent to 45°. 29 days after hatching, the total length of the juvenile was 16.9~19.8 (18.1±0.91, n=30) mm, and the number of fins reached an integer with 10 dorsal fins, 9 anal fins, and 7 ventral fins. The distribution of melanophore, such as the head, the center of the body, and the upper part of the fin, was different from that of the allied species during the postflexion larvae period, so the morphological characteristics could be distinguished.

• Korean Journal of Ecology and Environment
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• v.38 no.1 s.110
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• pp.73-82
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• 2005

This study was conducted, based on the field survey and laboratory observations, to elucidate egg developmental processes and their characteristics of the Korean slender gudgeon, Squalidus gracilis majimae. For the experiments, the mature adults were collected at the Woongcheon-Cheon Stream and Boreung Reservoir located in Boreung City, Chungnam Province and eggs were obtained from the natural spawning area. Morphological characteristics of the egg and embryonic development were summarized as follows: The shape of the fertilized egg was spherical, adhesive and transparent. The fertilized egg was 2.9${\pm}$0.3 mm (n = 30) in mean diameter under water temperature of $26{\pm}1.5^{\circ}C$, light white in color and had no oil droplets. After 20 minutes from the time of fertilization, a blastodisc was formed and divided into two cells at 48 minutes after fertilization. The blastular stage occurred at 5 hours 40 minutes after fertilization and the gastrular stage was detected at 8 hours 41 minutes after fertilization. The beginning of embryo formation was observed at 12 hours 58 minutes after fertilization and optic vesicles and 9 somites were discovered at 17 hours 05 minutes after fertilization. Differentiation of brains and embryo wiggling were observed at 37 hours 27 minutes after fertilization. Heart beating and the formation of melanophores in optic vesicles were detected at 44 hours 46 minutes after fertilization. The formation of pectoral fins and melanophores in the body were discovered at 50 hours 36 minutes after fertilization. Hatching occurred at 57 hours 49 minutes after fertilization. The newly hatched larvae were 3.3${\pm}$0.2 mm (n = 120) in total length. We believe that these results may contribute the species and population conservations under the situation of accelerated water pollution and the decreases of its diversity.

• Korean Journal of Ichthyology
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• v.11 no.2
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• pp.177-183
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• 1999

This study was conducted to observe the spawning behavior and early life history of chinese minnow, Rhynchocypris oxycephalus reared in the laboratory. The spawning period of Rhynchocypris oxycephalus is from May to June in nature. The eggs of Rhynchocypris oxycephalus were spawned on the sand and surface of the gravel. The fertilization eggs were demersal in shape and adhesive, released as a clump forming a thin layer and their diameter were 1.70~1.90mm (mean 1.80 mm, n=20). Hatching of eggs was started in 88 hour 45 minute after fertilization at water temperature $19{\pm}0.5^{\circ}C$ and finished in 90 hour. Newly-hatched larvae were measured 4.87~5.02 mm in total length (TL, mean 4.94 mm), mouth and anus were not opened. 6 days old larvae were 6.32~6.56 mm in TL (mean 6.44 mm). Yolk sac was almost absorbed, mouth and anus was began to open. 13 days old larvae were 6.74~6.91 mm in TL (mean 6.82 mm). Part of Dorsal fin was began to rising and myomere number was 15+23=38. 25 days after hatching, total length of larvae was 8.45~8.60 mm (mean 8.52 mm). Dorsal and anal fin rays became differentiated, and also caudal part of the notocord flexion was achieved at $45^{\circ}C$. In the time, growth rate was higher than the other stage. Aggregate numbers of all fin rays were completed at 16.39~16.57 mm in TL (60 days after hatching), at which time the larvae reached the juvenile stage, but fin-fold on ventral was remained yet. External features of adult specimens were almost completed at 80 day old juveniles (18.69~18.87 mm in TL).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.15 no.3
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• pp.241-250
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• 1982

The structure of gonads, gametogenesis and reproductive cycle of the cockle, Fulvia mutice, were studied mainly by histological observation. The materials were monthly sampled in the southern area of Yeosu from October 1980 to September 1981. F. mutica was monoecious. The gonads were situated between the liver tissues and the outer fibronuscular layers compacted by the connective tissue fibers and muscle fibers beneath the outermost layer of simple cuboidal epithelium. The gonad was composed of a number of the ovarian sacs and the testicular tubules which form the tubular structure. Testicular tubules in the mature stage sometimes contained 'testis-ova' The undifferentiated mesenchymal tissues and the eosinophilic cells were abundantly distributed on the germinal epithelium in the early development stage. With the further development of the ovary and testis, these tissues and cells gradually disapprared. The undifferentiated mesenchymal tissues and the eosinophilic cells are related to the growing of the oocytes and spermatocytes . Early multiplicating oogonium was about $10{\mu}m$ in diameter. As the oocytes grow to $27-34\times50-58{\mu}m$ by increasing cytoplasm, the oocytes connected to the basement membrane by their egg-stalks. The ripe eggs were about $60{\mu}m$ in diameter and they were surrounded by gelatinous membrane. Most male germ cells in mature stage were transformed into the spermatozoa and they formed the sperm bundles. After spawning, undischarged ripe eggs and spermatozoa remained in the ovarian sac and the testicular tubule respectively for some time, then they finally degenerated. Especially the early spent ovarian sacs in May did not contract significantly and then they took part in the secondary maturation within two or three months during the summer season. The monthly changes of the fatness well agreed with the reproductive cycle. The reproductive cycle of F. mutica could be classified into six successive stages : multiplicative, growing, mature, spent, degenerative and recovery stage. It seems that the spawning season is closely rotated to the water temperature, and the spawning occurs from May to October at about $20^{\circ}C$ in water temperature. The peak spawning seasons appeared twice a year between June and July and in September. Acknowledgement The authors wish to express their gratitude to Dr. Kim, In Bae, Dr. Chun, Seh Kyu and Dr. Yoo, Sung Kyoo of National Fisheries University of Busan and Mr. Min, Byoung Seo of National fisheries Research and Development Agency for their critical reading of the manu script.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.1
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• pp.68-80
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• 1984

Garolim Bay is not only important fishing ground but also expected area for the tidal power plant. The construction and operation of tidal power plant will make change the ecosystem of this bay. Therefore, the actual fisheries stocks should be precisely understood for the effect estimation and overall utilization of the bay after the construction of the tidal power plant. During the study period from January through December in 1981, forty-six adult fishes species, 3 species of fish egg and 25 fishes larvae species have occurred in the bay. Considering the result on monthly distribution of eggs and larvae, the inner area of the bay seems to be important as nursing ground of larvae spawned at the outside bay in winter, e. g., Ammodytes personatus, and Enedrias sp. This inner bay is also major spawning ground for many species spawning in spring and summer, e. g., Gobiidae, Konosirus punctatus, Engraulis japonica, etc. Taking into consideration the annual mean production for three years($1978{\sim}1980$), there are two major fishing seasons. The one is in May-June for Enedrias larvae stock, and the another in October-November for big eyed herring stock. For the mariculture stocks, short necked clam, oyster and laver are important species. After construction of the tidal power plant, the migratory species, i. e., larvae of Enedrias and Ammodytes personatus, Mugil cephalus, Konosirus punctatus, etc. will be directly damaged by the interuption of migration route. On the otter hand, the change of physico-chemical factors of seawater will also affect the ecosystem of the bay. Consequently, for the overall utilization of the bay after construction, the actual ecosystem including the fisheries stocks, must bs precisely revealed, and the mechanical designs, e. g., sluice position and its demension, should be also considered with these biological characters of the bay.