• Journal of Aquaculture
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• v.4 no.1
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• pp.31-66
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• 1991

This paper deals with the reproductive ecology e.g., number of the pre-spawning moults, morphological characteristics of the pre-spawning moult the common moult, daily ration druing a molting cycle mating behavior, structures of spermatozoa and spermatophore, structure of vas deferens, mechanisms of the oviposition and brooding into the egg-chambers, a suitable time for the artificial mating and fertilization, time sequence of the oviposition and brooding into egg-chambers from the copulation, responses to temperature and chlorinity on the egg development and hatching, effect of temperatures on duration of egg development, physical mechanism of the egg hatching, to make an attempt for the artificial spawning and brooding to establish a suitable system of the artificial seedling-production for the aquaculture. 1. Females molted commonly $8{\~}10$ times at an interval of $17{\~}18$ days at $28^{\circ}C,\;3.26\~4.35\%_{\circ}$ while the prespawning moltings were $4{\~}5$ times at an interval of $13{\~}14$ days. The suitable state for artificial copulation was within 14 hours elapsed from the prespawning moltings (most suitable state was within 8 hours). Males discharged a gelatinous spermatophore and placed it on the females sternum during copulation. Oviposition was seen $6{\~}17$ hours after copulation. External fertilization was considered to take place at oviposition. Fertilized eggs held in egg-chambers forming between pleopods were about $5000{\~}6000$ in females those sizes about 6.5 cm in body length. 2. Eggs immediately after oviposition were elliptic shape, measuring $0.58{\times}0.48$ mm up to hatching. Their sizes increased with egg development and finally reached $0.85{\times}0.54$ mm up to hatching. The relationship between the long axis of the egg(Y in U) and days elapsed(X) was expressed as Y= 5.60194 + 0.007358X. The eggs performed superficial cleavage and their cleavage furrows became visible at the 4-daughter-nucleus stage. The eggs showed normal development up to hatching at water temperature range of $22{\~}30^{\circ}C$ (optimum temperature : $26{\~}28^{\circ}C$) and at chlorinity range of $0.00\~6.64\%_{\circ}$ (optimun chlorinity : $2.21{\%}_{\circ}$). The relationship between incubation period (Y in days) and water temperature(X in $^{\circ}C$) could be expressed as Y= 50.803-1.3555X. The eggs hatched $12{\~}13$ days after oviposition at $28.0{\~}28.6^{\circ}C$ 3. The pre-spawning moltings were appreciably different in the morphologic structure from those of common moltings. Breeding setae and dresses were formed on the thoracic regions, abdominal epimerae and the bases of the first to fourth pleopods in order to prepare and support oviposition, transfering and supporting eggs in egg-chambers up to hatching. These supplementary breeding organs were observed only at reproductive seasons.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.3
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• pp.296-301
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• 2017

We conducted a study to 1) determine the indicators of gonadal maturity in male and female Korean walleye pollock Theragra chalcogramma for the purposes of artificial insemination; 2) establish the RNA/DNA ratio of mature eggs in this species; and 3) monitor the effect of refrigerated storage on egg viability and the motility of sperm collected from dead adult males. During the spawning season, the color of female gonads changed from orange to transparent, and that of male gonads changed from pale orange to milky white. The DNA content and RNA/DNA ratio of mature eggs were maintained without significant changes for approximately 6 h when eggs were preserved at $4^{\circ}C$. Sperm could be obtained from both milt and undiluted semen. Sperm obtained from milt ceased moving on the second day after isolation, while over 60% of sperm obtained from semen showed movement until the 13th day. Seven attempts were made to artificially inseminate mature eggs, of which two resulted in successful fertilization. The successful inseminations produced 94,000 and 5,000 fertilized eggs, respectively. This study shows that artificial insemination of walleye pollock is a viable strategy when natural propagation is not possible.

• The Korean Journal of Malacology
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• v.20 no.1
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• pp.75-84
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• 2004

Reproductive cycle, the condition index, sex ratio of the Pacific oysters, Crassostrea gigas were investigated by histological and morphometric data. The specimens were collected in the two oyster farms of Geoje and Namhae, Gyeongsangnam-do, Korea, from November 1995 to October 1996. Growth of shell length in two regions was similar, but growth of total weight of the oyster in Namhae was faster than that in Geoje oyster farm. The spawning periods in female and male clams were from July to October in Geoje and from June to October in Namhae oyster farm. Ripe oocytes were approximately 50 m in diameter. The reproductive cycle of in females and males in Geoje and Namhae oyster farms can be divided into five successive stages: early developing, late developing, ripe, partially spawned and spent/inactive. Monthly changes in gonad developmental phases showed somewhat different patterns between female and male clams except for the spawning period. On the whole, however, monthly changes in the gonad developmental phases showed a similar pattern in the same sex. The sex ratios of females to males in Geoje and Namhae oyster farms were not significantly different from a 1:1 sex ratio ($x^2$ = 0.55 (p > 0.05) in Geoje and $x^2$ = 0.27 ( p > 0.05) in Namhae). Artificial induction of maturation by heating of adult oysters (two-year-old) was investigated from 17 January to 18 March in 1996. Maturity at the fixed water temperature group of $20^{\circ}C$ was 80%, it showed the highest maturity of experimental groups cultured for five weeks. The survival (%) of Crassostrea gigas in the raised water temperature experimental groups (15, 20, $25^{\circ}C$) were over 98.5%, as similar to the control group (100%). But, the survival of C. gigas in the fixed water temperature experimental groups (15, 20, 25, $30^{\circ}C$) were decreased with the increase of the water temperatures. In the fixed water temperature experimental group of $30^{\circ}C$, the survival was 51.1%. Base on these results, the fixed water temperature of $20^{\circ}C$ was the best condition for artificial induction of sexual maturation.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.6 no.3
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• pp.141-147
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• 2013

An artificila fish-reef is a artificail structure installed at marine ranching under the littoral sea. The artificial fish-reefs provide the function of fish spawning ground, habitation, nursery ground, and enhance the productivity of fising industry devastated by environmental pollution. After the installation of artificila fish-reef, continuous monitoring is demanded to check the validity of artificila fish-reef plan. However, the support of follow-up management is impossible because of the lack of a huge budget and professional manpower. Therefore, the artificial fish-reef combined with IT devices can be controled IT devices through the IT artificial fish-reef management system, and collect the marine environment information for the fair management. This paper shows the example of systematization for the management of artificial fish-reef based on the marine rancing management system.

• Development and Reproduction
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• v.15 no.2
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• pp.133-141
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• 2011

The marine ornamental industry has become a multi-billion dollar industry these days. As developing, however, this industry has been criticized for the indiscriminate captures and the destruction of the surrounding environment. To circumvent these problems, it is suggested to breed the organisms artificially. While clownfishes Amphiprion sp. and Premnas sp. are the most famous ornamental organisms in the trade, few studies are yet available on the culture and commercial production of these fishes. These studies were performed to investigate the spawning periodicity, behavior and the habits during egg incubation, and to provide the information on the mass hatching system. The spawning periodicity and frequency were different in 4 pairs under the constant condition, temperature, salinity and photoperiod. On the contrary, the male's behaviors for egg incubation are almost same in the all. The egg-fanning activity of the male increased as the developing eggs reaching to the hatching day. Based on the above results, we designed a new artificial hatching system, the rotating type (RT), and compared it with the aeration type (AT) and spray type (ST) that were previously described. RT showed higher hatching rate of 87.3% than AT (74.4%) and ST (60.5%). Also, there were no significant differences in the hatching rate regardless of the number (2, 3, 5) of hatching plates. We suggest RT may accommodate various number of hatching plates and constitute a better hatching system for clownfishes.

• Journal of Aquaculture
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• v.21 no.1
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• pp.34-40
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• 2008

This study investigated the effect of rearing conditions on the spawning habit, juvenile growth and larvae development of Marphysa sanguinea, to develop techniques of its artificial seed production. M. sanguinea released trochophore larvae around the burrow when the water temperature was from $18^{\circ}C$ to $22^{\circ}C$. Larvae floated away after staying in the burrow for a while. Larvae secreted mucus eight days after release, covering their whole body with it, and developed ten somites 20 days after release. In preference of juveniles in different grain sizes of sediment, the highest survival rate was made in the grain substrate of $1{\sim}2$ mm in the mean diameter, but the lowest was in the $2{\sim}3$ mm grain substrate. Optimum growth was obtained at the rearing temperature of $24^{\circ}C$(SGR 1.10%), and it reached over $2{\sim}3$ times higher weight gain and specific growth rate than those reared at $21^{\circ}C(0.64),\;18^{\circ}C(0.56)$ and $15^{\circ}C$(0.42) for 50 days. Salinity also made a great difference in the growth and survival rate. The highest weight gain and growth rate were shown when the juveniles were reared at salinity 30 psu.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.9
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• pp.2307-2312
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• 2014

Artificial reef refers to various structures that facility to construction field format and spawning of marine organisms, sea ranch, forest of the sea, and sea jungle artificially in water, Build a production stable base of marine products, thereby contributing to an increase in the income of fishermen. In the management of an artificial reef, the calculation of the number of square reefs may be that it is a method to perform the submersible is an important part of maintenance is correct. However, cost and diving personnel, depending on the diving situation, there is a difficult thing to implement to coast across the country. Therefore, In this study, We calculated the volume using the multi-beam Echo Sounder and side scan sonar for the reefs of the rectangle are the existing installation. And proposes the improvement of the estimation in accordance with the volume coefficient reef.

• Korean Journal of Artificial Intelligence
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• v.5 no.2
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• pp.26-42
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• 2017

This study perceived that there are limits to prompt and accurate monitoring when an accident occurs and the correct information of egg production stage, such as the date of spawning, cleaning, and refrigerating cannot be identified, since eggshell codes using barcode only show numbers identifying a city and province and the name of producers. To fix this problem, this study partially suggested the RFID (Radio Frequency Identification) technology and IoT-based Connected System. The proposed system in this study shares data with related agencies as the system of agricultural and livestock product information runs as the main server, and the database information of the proposed system is provided by farmhouses, distributors, and sellers. Through various media such as a webpage or mobile application built to provide the relevant information, customers can search and obtain information about agricultural and livestock products they want. Since the information on an entire process is open to the public, information ranging from simple to clear, additional ones such as hazardous elements can be viewed.

• Fisheries and Aquatic Sciences
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• v.16 no.1
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• pp.15-23
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• 2013

Normal embryonic development at a constant temperature ($18^{\circ}C$) has been described for the Siberian sturgeon Acipenser baerii (Acipenseriformes). Hormone-induced spawning and artificial insemination were performed to prepare embryonic batches for embryologic examination. After insemination, early cleavages of the Siberian sturgeon embryos continued for 7 h post-fertilization (HPF), showing the typical pattern of uneven holoblastic cleavage. Blastulation and gastrulation began at 9 HPF and 19 HPF, respectively. Epiboly formation (2/3 covered) was observed at 25 HPF during gastrulation. Neurulation was initiated with the formation of a slit-like neural groove from the blastopore at 33 HPF. During neurulation, the primary embryonic kidney (pronephros) and s-shaped heart developed. The embryos underwent progressive differentiation, which is typical of Acipenseriform species. A mass hatching was observed at 130 HPF, and the average total length of the hatched prolarvae was 10.5 mm. The hatched prolarvae possessed a typical pigment plug (yolk plug). The results of this study are valuable not only as a reference guide for the artificial propagation of Siberian sturgeon in hatcheries but also as the basis for the derivation of developmental gene expression assays for this species.

• Microbiology and Biotechnology Letters
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• v.9 no.3
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• pp.109-116
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• 1981

Three edible species and one species utilized as drug were selected from wild mushrooms collected from mountains and fields throughout Korea during 1977 to 1979 for artificial cultivation. The media, MES for G. lucidum, MHS for P. rudis and MSES and MHS for P. adipose and Pluteus sp. were selected. The range of optimum pH was 4.0 to 5.0 in citric acid-sodium phosphate dibasic for the tested species. The range of optimum temperature for the mycelial growth of G. lucidum and P. adiposa was 25 to 3$0^{\circ}C$ and 30 to 35$^{\circ}C$ for P. rudis and Pluteus sp. For the moisture content 75 to 80% (w/w) in the substrates, the mycelial growth of most tested species was rapid. As the spawning substrates, poplar sawdust for G. lucidum and Pluteus sp., oak sawdust for P. rudis and wheat for P. adipose were selected, respectively. In this experiment, the fruit bodies of all tested species were appeared. Among them, G. lucidum for medicinal purpose and P. adiposa and Pluteus sp. for sources of new edible mushrooms seems to be possible. However, the sporophores of P. rudis were not adequate as an edible mushroom for the commercial due to the leathery flesh.