• The Korean Journal of Malacology
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• v.24 no.2
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• pp.153-159
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• 2008

We investigated artificial mass seed production of a Chinese scallop, Patinopecten yessoensis, in 2004. The GSI(gonad somatic index) of the Chinese scallop, P yessoensis was 17.2 on mid-February, 20.2 on mid-March, while that of Korean scallop, P yessoensis was 6.9 on mid-February, 10.8 on mid-March. Matured 120 females and 350 males were selected for artificial mass production. They were exposed in air for 1 hr at over $20^{\circ}C$, and placed into a spawning tank(20 ton) containing sea water treated with UV radiation at $12^{\circ}C$. We gained a total of 228,000 thousand scallop embryos between March 10th and 15th, and reared larvae at the indoor tank during 25 days. When the mean shell length of larvae reached 250 ${\mu}m$ and they have eye-spots, the number of pre-settling larvae was 47,500 thousand. We gained 1,850 thousand attached scallop spats from two kinds of collectors. Attached spats were reared in indoor tank for different periods from 5 days to 60 days. They were divided into 5 groups according to the length of reared days. Each group of attached spats was moved to intermediate rearing sites at Yangyang fishing port in Gangreung-city for acclimation to ocean environments. The highest survival rate of attached spats was 13.0% shown at the group reared for 12 days, but the significant difference in their growth was not found between the groups. The shell length of artificial attached spats increased from 0.9 ${\mu}m$ on July 10th to 24.7 ${\mu}m$ on December 16th with the survival rate of 85.0% while that of natural attached spats increased from 0.6 ${\mu}m$ on July 10th to 23.9 ${\mu}m$ on December 16th with the survival rate of 85.7%.

• Journal of Aquaculture
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• v.20 no.4
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• pp.219-225
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• 2007

This study investigated the correlationship between artificial maturation season and reproduction coefficient of cultured eel Anguilla japonica from May (spring) to next January (winter). The brood stock, female eels ($400{\sim}600\;g$) were artificially matured by weekly intramuscular injections of salmon pituitary extracts (SPE, 20 mg/fish) to induce a completion of vitellogenesis. After completion of vitellogenesis, final oocyte maturation and ovulation was induced by injection of $17{\alpha}$, $20{\beta}-dihydroxyprogesterone$ (DHP) at about $2\;{\mu}g/g$ body weight. Most fish ovulated $15{\sim}18\;h$ following the DHP injection. The ovulated fish were induced to natural spawning or artificial fertilization by the dry method. Males ($200{\sim}350\;g$) were received weekly intramuscular injections of human chorionic gonadotropin (HCG) at a dosage of 1 IU/g body weight to induce testicular maturation and spermiation. Seasonal reproduction coefficient which includes the rate of ovulation, buoyancy, fertilization and hatching of eggs in the artificially matured eel during spring to summer ($May{\sim}July$) were significantly higher than the other season, while there were no significant difference among spring and summer (P<0.05). Furthermore, the number of eggs spawned and larvae hatched in the artificially maturated eel during spring to summer ($May{\sim}July$) were significantly higher than the other season, while there were no significant difference in spring and summer (P<0.05). These results indicate that artificial maturation by hormone treatment of A. japonica was successful only during spring to summer, which is the maturation period in the wild stock in nature. Consequently, it is possible to determine the period of artificially induced sexual maturity by the reproduction coefficient which includes the rate of ovulation, buoyancy, fertilization and hatching of eggs in the cultured eel A. japonica.

• The Korean Journal of Malacology
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• v.18 no.2
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• pp.83-91
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• 2002

Reproductive cycle of natural population and artificial control experiments of gonadal development by the conditions of water temperatures-feeding and starvation of Ruditapes philippinarum were investigated by histological observations. The reproductive cycle of natural population in females and males can be categorized into five successive stages; early active (February to March), late active (April to May), ripe (April to August), partially spawned (May to October), and spent-inactive stage (August to March). In the artificial control experiments, gonadal development of this species was inhibited by the low water temperature (10$^{\circ}C$). In the experimental group which was exposed to artificial high water temperatures of 19$^{\circ}C$ and 22$^{\circ}C$, gonadal development was accelerated by the higher water temperatures and was faster (about one month) than that in natural populations. In the high water temperatures-feeding experimental group, the gonadal developmental phase was faster in the small-size group than that in the large-size group, and was faster in lower water temperature (10$^{\circ}C$)(p=0.01). The gonad developmental phases in the high water temperature (22-28$^{\circ}C$)-starvation experimental group showed faster (paired sample t-test, p=0.004) than those in the high water temperature-feeding group in females and males. In the high water temperature-feeding experimental group of female and male gonadal developments of small sized group were more sensitive than those in large sized group after 42 days cultivation, However, the gonadal development of male was more sensitive to the lower water temperature than female. On the whole, sexual maturation in the high water temperature experimental group was faster than those in the low water temperature group, and showed a significant difference (paired sample t-test, p=0.001) between female and male. In the starvation experimental group after 42 days, gonadal developments in the high water temperature-large male group showed faster than those in the high water temperature-large female group. However, in small size, gonad developmental phases showed the same pattern between feeding and starvation experimental groups. During the main spawning season, in the high water temperature-starvation experimental groups in females and males, their gonadal development showed faster than that in higher water temperature-feeding experimental group regardless of their sexes and individual sizes and showed a significant difference (paired sample t-test, p=0.004).

• Korean Journal of Environmental Biology
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• v.27 no.4
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• pp.369-374
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• 2009

The stumpy bullhead (Pseudobagrus brevicorpus) endemic to Korea is one of critically endangered freshwater fish species. To provide baseline data for its captive breeding and reintroduction we investigated basal characteristics on its growth and sexual maturation in an artificial rearing environment. After 698-day rearing the stumpy bullhead grew up to $89.22{\pm}10.29\;mm$ in total length (TL) and $70.93{\pm}7.68\;g$ in total body weight (BW)($BW=5\times10^{-5}\;TL^{2.678}$; $R^2=0.995$), and showed survival rate of 74.2%. The sex ratio was 1 (471 females) : 1 (473 males), and males ($TL=87.44{\pm}1.07mm$; $BW=8.43{\pm}0.31\;g$) showed significantly faster growth than females ($TL=78.38{\pm}0.92mm$; $BW=6.38{\pm}0.20\;g$) after 663-day rearing. However, condition factor of females was significantly higher than that of males (P<0.05). The number of eggs per female ranged from 508 to 867 (average 734), and their diameters ranged from 0.04 to 1.65 mm. The females which reared about two years in the laboratory condition was able to spawn in the early June after 1~2 days of human chorionic gonadotropin (HCG) injection. The number of hatched fries ranged from 113 to 338 (average 216).

• Journal of Korean Society of Environmental Engineers
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• v.36 no.12
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• pp.828-836
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• 2014

The purpose of this study evaluates the water quality of artificial deep pool (ADP) during the late spring and summer. we monitored the water quality, as pH, dissolved oxygen (DO), temperature and conductivity at two stations (St. 1. open water, St. 2. in the ADP). The water quality in the ADP is very stable, and temperature and DO are lower than the open water (average value; temperature $1.4{\sim}3.2^{\circ}C$, DO 2.4~3.6 mg/L). In particular, daily variation of temperature in the open water showed above $4^{\circ}C$, but ADP remained stable. The water quality was analyzed using two-way analysis of variance (ANOVA). The results of the analysis showed difference about temperature, pH, DO, conductivity (two-way ANOVA, p<0.05). The ADP has created an aqua environment in thermal and DO gradients by depth. About 1.2 m, Temperature and DO were sharply decreased. The Rhodeus uyekii is dominant species in pond of this study. The ADP offers optimum water temperature ($16.5{\sim}18.5^{\circ}C$) to the Rhodeus uyekii about spawning. Consequently, the ADP offers stable habitat than open water for fish and aquatic organisms during the summer. It is also a good shelter for fish from a thermal stress.

• Korean Journal of Animal Reproduction
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• v.16 no.1
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• pp.63-76
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• 1992

This study was carried out to investigate the appearance time of the second polar body for producing Gynogenesis or Triploid which could be obtained by arresting the second polar body by cold shock, and then blastoderm was used to measure fertility that revealed the nature of oogenesis, the effects of water temperature on fertility, hatchability, abnormality, viability and growth rate, and the water temperature and the breeding methods to prevent early death of larvae in Korean loach(Misgurnus anguillicaudatus) ; the results obtained in this study were summarized as follows. The second polar body was observed ont he surface of plasma disc close to micropyle within 10~40 min after fertilization at 29$^{\circ}C$. Artificial inseminatin had to be done immediately after the egg spawning because the spermatozoa of loach their mobility within 2 minutes when they were exposed to water. The amount of time needed to reach at blastoderm stage was 12 hours if fertilized eggs were incubated at 16$^{\circ}C$, 8 hours at 19$^{\circ}C$, 6 hours at 21$^{\circ}C$, 5 hours at 23$^{\circ}C$, 4 hours at 26$^{\circ}C$ and 3 hours 30 min at 29$^{\circ}C$ showing the shorter time for development of eggs at higher temperature. Fertilization rates in water temperatures of 19$^{\circ}C$, 21$^{\circ}C$, 23$^{\circ}C$, and 26$^{\circ}C$ were higher than those of water temperatures, 16$^{\circ}C$ and 29$^{\circ}C$. Water temperatures at 19$^{\circ}C$, 21$^{\circ}C$, and 23$^{\circ}C$ showed higher hatching rates that those of 16$^{\circ}C$, 26$^{\circ}C$, and 29$^{\circ}C$, while abnormal rates in 16$^{\circ}C$, 19$^{\circ}C$, 21$^{\circ}C$ and 23$^{\circ}C$ were lower than that of 26$^{\circ}C$ and 29$^{\circ}C$. Water temperatures at 16$^{\circ}C$, 19$^{\circ}C$, 21$^{\circ}C$, 23$^{\circ}C$ and 26$^{\circ}C$ respectively, were more different than 29$^{\circ}C$ in survival rates. The embryos were hatched at 72 hours after fertilization in 16$^{\circ}C$ water temperature, 48 hours in 19$^{\circ}C$, 40 hours in 21$^{\circ}C$, 32 hours in 23$^{\circ}C$, 25 hours in 26$^{\circ}C$, and 16 hours in 29$^{\circ}C$. Within three days after hatched out, the larvage grew 3mm in total length, the yolk granules were entirely consumed and the head and the trunk became thicker. Within 45 days after hatched out, the larva grew 25mm at 29$^{\circ}C$, 21mm at 26$^{\circ}C$, 16mm at 23$^{\circ}C$, 15mm at 21$^{\circ}C$, 12mm at 16$^{\circ}C$ in a 30 litreglass aquarium.

• The Korean Journal of Mycology
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• v.9 no.3
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• pp.123-128
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• 1981

Three edible species, e.g. Lyophyllum sp. and Armillaria mellea introduced from Japan in 1979 and Auriaularia auricula-judae from Taiwan in 1978 were selected for artifcial cultivation. The media, MSDS for Lyophyllum sp, MHS and PDS for A. auricula-judae, and MSDS and MHS for A. mellea were selected. The range of optimum pH of Lyophyllum sp. was 6.0 and pH 8.0 for A. auricula-judae and pH 6.0 to 7.0 for A. mellea. The range of optimum temperature for the mycelial growth of Lyophyllum sp. was 25 to $30^{\circ}C,\;30^{\circ}C$ for A. auricula-judae and $25^{\circ}C$ for A. mellea. When the moisture content 75 to 80% (w/w) in the substrates, the mycelial growth of Lyophyllum sp. and A. auricula-judae, was rapid. 65% (w/w) for A. mellea. As the spawning substrates, wheat for Lyophyllum sp. oak sawdust for A. auricula-judae and poplar sawdust for A. mellea were selected, respectively. In this experiment, yields of Lyophyllum sp. and A. auricula-judae were high on the poplar sawdust added 20% (w/w) of rice bran. Lyophyllum sp. and A. auricula-judae for sources of new edible mushrooms seems to be possible.

• Korean Journal of Ichthyology
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• v.5 no.2
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• pp.151-159
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• 1993

Greeling, Hexagrammos otakii Jordan et Starks is commonly found at the coastal waters of Korea and Japan. The authors carried out the artificial insemination in the laboratory on Dec, 17, 1987, and reared the hatched larvae in an aquarium. The eggs were demersal and adhesive, and their diameters were 2.00~2.15mm. Color of yolk was light yellow in the early stage, and then turned to orange before hatching. The yolk had numerous tiny oil globules. Hatching began about 477hours after insemination under water temperature of $10.0{\sim}14.5^{\circ}C$. The newly hatched larvae were elongate in shape and 7.48~8.25mm in total length(TL) with 49~50 myomeres. The larvae absorbed the yolk material and oil globules completely in 5days after hatching and became postlarvae. In 17days after hatching, mean total length of the larvae was 9.85mm, and the caudal notochord flex at $45^{\circ}$. In 23days, total length reached 10.54mm. The part of the fin-fold of the future dorsal and anal fins became high. Spawning season of the Greenling is known to be from November to January in the southern coast of Korea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.3
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• pp.230-237
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• 2000

An ecological study of the benthic macrofauna was carried out using a modified van Veen grab in September 1997, in Namdaechon estuary, Yangyang, Korea. A total of 17 macro-invertebrates was collected and examined from eleven stations in the study area, including 3,795 individuals and 738.63 g wet weight. Arthropods, annelids and molluscs were most abundant and occupied more than $95{\%}$ of the total number of species, individuals and biomass. Namdaechon estuary in Yangyang was very poor in macrobenthic biodiversity, and numerically dominated and characterized by the polychaetes Heteromastus filiformis, Hediste japonica, Eteone longa, an unidentified oligochaete Oligochaeta sp., a corbulid bivalve Corbicula japonica, and an estuarine isopod Cyathura higoensis. Species composition, species dominance, density, and species evenness were compared among stations. The macrofaunal azoic zone appeared in the bottom of 7 m in depth nearby the artificial bank to catch the salmons to return to the livers for spawning. It probably resulted from the oxygen depletion following strong stratification in summer, which can cause major effect on the ecological conditions and then finally kill bottom macro-invertebrates in this area. Moreover, some opportunistic species thrived in nearby another station and this is of vital importance in terms of the ecological succession in a benthic polluted area.

• Korean Journal of Ecology and Environment
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• v.33 no.3 s.91
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• pp.282-294
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• 2000

The reproductive ecology and the early life history of Macropodus chinensis were investigated in aquarium. Mature male made the bubble nest and spawned with wrapping the female and reverse posture. The parental male protected the offspring until the larvae depart the bubble nest. Egg productivity and egg hatching rate were the highest at water temperature in $28^{\circ}C$ and $26^{\circ}C$ respectivity than any other artificial temperature. The eggs were buoyant, globular and 0.95${\sim}$1.05 mm in diameter. Cleavage was progressed at intervals of 15 minutes. Eggs hatched in 42${\sim}$44hours after fertilization and the newly hatched larvae were 3.0${\sim}$3.2 mm in total length. The lawae were 4.5${\sim}$5.4 mm in 4${\sim}$5 days after hatching and fed on the food with dispersion from the nest. In 40${\sim}$45 days after hatching, all fin rays completely developed, and juveniles reached 18.2${\sim}$23.5 mm in total length. In 90${\sim}$110 days after hatching, body from of young fishes were similar to adult with 37.4${\sim}$48.2 mm and represented secondary sexual characters longer than 45.0 mm in total length, and about 120 days, fishes began spawning(water temperature for ontogenesis: $26.0{\pm} 1^{\circ}C$).