• Korean Journal of Ichthyology
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• v.30 no.2
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• pp.75-83
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• 2018

This study is to observe species identification and early life history of Korean endemic species of Tanakia latimarginata and to use it as a basis for taxonomic studies. As a result of morphological identification, a dark band appeared at the margin of the anal fin, and the ovipositor color of the female was light orange. The shape of the egg was fusiform and sticky. The egg size (long${\times}$short diameter) averaged $4.41{\times}1.44mm$. The incubation time was 126 hours after the fertilization at an average water temperature of $21.0^{\circ}C$. Immediately after hatching, the larvae had egg yolk at an average total length of $5.91{\pm}0.18mm$ (n=5). At 18 days after hatching, the trunk fur was developed in the caudal fin with an average total length of $8.02{\pm}0.08mm$ (n=5). At 41 days after hatching, the larvae absorbed egg yolk at an average total length of $8.70{\pm}0.23mm$ (n=5). At 80 days after hatching, the average length of the fins was $12.6{\pm}0.28mm$ (n=5). The number of fin of the dorsal fin was iii.8, the anal fin iii.9~10, the caudal fin 19, lateral line scales 32~35 were similar to their brood stork.

• Ecology and Resilient Infrastructure
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• v.2 no.3
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• pp.216-223
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• 2015

The conservation project to protect an endangered fish, Gobiobotia naktongensis was executed against declining the gene diversity of the fish after the construction of Youngju Dam in a sand-bed stream (Naeseongcheon Stream). We tried to move the populations of G. naktongensis from submerged planned sites to alternative habitats, bred artificially and augmented the juveniles to optimal habitat, and monitored the results of the restoration implementation. No entity of G. naktongensis was confirmed at the planned submerged sites despite attempting to capture more than 8 times and eventually the movement to alternative habitat could not be implemented. About 40 individuals of G. naktongensis were captured in the Naeseongcheon Stream and a total of 5,000 individuals were artificially spawned up. The population of juvenile inherited the genetic diversity from the brood stock. The bred juveniles were discharged at the selected optimal site that had a habit condition what was similar to their natural habitat. The micro-dispersion around the discharging area was found at the early stages of the augmentation. The re-capturing rate of discharged juveniles was reduced as time passed. The discharged juveniles seemed to adapt to the natural environment of Naeseongcheon Stream. The observation of their high abdominal distension and excrement demonstrated that the juveniles fed successfully in the discharging area. Therefore, securement of genetic homogeneity and enhancement of restoration population of G. naktongensis in upstream and downstream of Youngju Dam site from the artificial seed producing seemed to be primarily successful and long-term monitoring and analysis of the effect was expected to be necessary.

• Journal of Sericultural and Entomological Science
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• v.50 no.2
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• pp.87-92
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• 2012

We constructed the fibroin H-chain expression system to produce Discosoma sp. red fluorescent protein variant2 (DsRed2) in transgenic silkworm cocoon. Fluorescent cocoon could be made by fusing DsRed2 cDNA to the heavy chain gene and injecting it into a silkworm. The DsRed2 fusion protein, each with N- and C-terminal sequences of the fibroin H-chain, was designed to be secreted into the lumen of the posterior silk glands. The expression of the DsRed2/H-chain fusion gene was regulated by the fibroin H-chain promoter. The use of the 3xP3-driven EGFP cDNA as a marker allowed us to rapidly distinguish transgenic silkworms. The EGFP fluorescence became visible in the ocelli and in the central and peripheral nervous system on the seventh day of embryonic development. A mixture of the donor and helper vector was micro-injected into 1,020 Kumokjam, bivoltin silkworm eggs. We obtained 6 broods. The cocoon was displayed strong red fluorescence, proving that the fusion protein was present in the cocoon. Accordingly, we suggest that the DsRed2 fluorescence silk will enable the production of novel biomaterial based on the transgenic silk.

• Development and Reproduction
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• v.12 no.3
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• pp.261-266
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• 2008

In the present study, we investigated in vivo effects of Manchurian trout recombinant gonadotrophin hormone (mt-rGTH) on the induction of maturation in female eel, Anguilla japonica. The brood stock, female eel (450$\pm$50 g) were weekly injected intramuscularly with different doses of 0.1, 1, 10 ${\mu}g\m{\ell}$/fish (mt-rFSH or mt-rLH) for 10 week. The effects of r-mtGTH were analyzed by gonadosomatic index (GSI), ovarian follicle diameter and sex steroid levels. All groups did not exhibit significant differences in the GSI values. Whereas plasma testosterone (T) and estradiol-17$\beta$ (E2) levels did not change significantly in control group, plasma levels of T and E2 by injection of the r-mtFSH or r-mtLH were increased at 2 or 4 week after injection. In addition, injection of the mt-rFSH (1, 10 ${\mu}g/m{\ell}$/fish) or mt-rLH (0.1, 1, 10 ${\mu}g/m{\ell}$/fish) significantly increased follicle diameters comparing to the control group. These results demonstrate that the recombinant hormone may affect early ovary development and maturation in female eel. Taken together, these results suggest that the recombinant Manchurian trout FSH and LH are effective for reproductive activities in female eel.

• Korean Journal of Environment and Ecology
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• v.36 no.6
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• pp.615-626
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• 2022

This study investigated the habitat characteristics and spawning ecology of Hippocampus haema (Syngnathidae) in Soando Island, Korea, from May 2015 to December 2016. The survey site where seahorses inhabit was mainly formed by seagrass of Zostera marina populations. Total density and biomass (Mean±SE) of Z. marina were the highest at 136±14.4 shoots/m² and 489.8g DW/m², respectively, in spring (May), while the total density was lowest at 93±7.0shoots/m²in autumn (October), and biomass was the lowest and at 122.3g DW/m² in winter (February). During the study period, 293 individuals were identified through a diving and kick net survey, and the total length of H. haema ranged from 10.1 to 87.0mm. Male individuals nurturing fertilized eggs or larvae appeared beginning in May and were collected until October in both 2015 and 2016. Juvenile individuals were captured beginning in July 2015 and June 2016. As a result of a comprehensive analysis of the spawning season characteristics, it was estimated that the spawning season of H. haema was from April to October. The number of fertilized egg or larvae inside the male brood pouch were 38.3±14.8 (20-76), and the number of fecundity identified from female were 47.2±8.6 (31-59). The male-to-female ratio of H. haema was 1:1.7, indicating the dominance of males.

• Korean Journal of Ichthyology
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• v.35 no.4
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• pp.253-262
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• 2023

This study compared the results of observing the early life history of Gymnogobius urotaenia, which lives in Hwangbocheon Stream, an inflow stream on the east coast, with the differences between fish of the same Gobiidae fishes. In May 2022 and 2023, fertilized eggs and brood stork scattered under rocks were captured twice in Hwangbocheon Stream. The spawning amount was 827~1,540 and the orchid was a elliptical in shape with a size of 3.21×1.07 mm. The stage of ovulation observed in the laboratory was 16 cells, and hatching began after 193 hours. The breeding water temperature range was 18.8~19.3℃. Newly after hatching larvae, the yolk sac with a total length of 3.84~4.33 (average 4.10±0.17, n=30) mm, and the anus was not open. 6 days after hatching of incubation, the total length was 5.32~6.11 (average 5.67±0.25, n=30) mm, absorbing all egg yolk and transitioning to the preflexion larvae, ingesting food, and developing a keynote on the tail fin. 15 days after hatching, the end of the urostyle end was completely bent at 45° with a total length of 7.33~8.52 (average 7.81±0.46, n=30) mm and transitioned to postflexion larvae, and melanophore developed throughout the body. 38 days after hatching, the total length is 22.1~26.1 (23.8±1.36, n=30) mm and the number of fins (6 first dorsal fins, 11 second dorsal fins, and 11 anal fins, 12 ventral fins) is all the number of fin base became integer and transferred to the juvenile. As a result of the study, it was possible to distinguish the melanophore of postflexion larvae of G. urotaenia from other postflexion larvae Gobiidae fish in that they were distributed throughout the body of half the body and tail.

• Korean Journal of Ichthyology
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• v.36 no.1
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• pp.1-9
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• 2024

This study investigated the early life history of the Boleophthalmus pectinirostris living in the southern coastal Yeoja-man and compared the results with the same Gobiidae fishes. The brood stork used in the study were captured with bare hands in the tidal flats of Beolgyo-eup, Jeollanam-do, in June 2015. The amount of spawning was 411~11,688, and the eggs were short oval and the size was 1.40×0.72 mm. The time of hatched took 91 hours and 35 minutes at a water temperature of 25~27℃. Newly hatching larvae, the yolk sac had a total length of 3.02~3.31 (average 3.17±0.08, n=30) mm and did not eat rotifer. 4 days after hatching, the total length was 3.31~3.52 (3.43±0.07, n=30) mm, and as the mouth and anus opened, the fish transitioned to the preflexion larvae and fed. 14 days after hatching, the total length was 5.06~5.25 (5.16±0.06, n=30) mm, and the distal end of the vertebra was completely bent at 45° and the transitioned to the postflexion larvae. 41 days after hatching, the total length was 14.3~16.8 (15.4±0.85 mm, n=30), and the number of fins reached an integer of 5 first dorsal fins, 26~27 second dorsal fins, 24~27 anal fins, and 6 ventral fins, and the transitioned to the juveniles. As a result of the study, star-shaped melanophore were deposited from the front of the pectoral fin to the base of the caudal fin, which distinguished them in form from other postflexion larvae of Gobiidae fishes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.49-54
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• 2017

We collected and reared Theragra chalcogramma walleye pollock brood-stock for use in natural spawning tests and undertook to obtain domestic pollock via fertilized egg capture, development of fertilized eggs, and absorption of yolk sac after hatching. Whole pollock were caught with trammel and set nets and immediately placed in a deep-sea water tank. Adults were the most common pollock age group (43.0%; n = 86) among the 254 pollock captured in March 2014 with 57.9% (n = 147) being captured off Southern Gosung, Korea. The main spawning period of pollock is February (spawning phase of 91% of pollock). From the deep-sea tank, we collected 1640 mL of naturally fertilized eggs (~820,000 eggs) from 12 spawning events occurring between February 4 and 22 2015. The floating/ live eggs were maintained in deep-sea water tanks at $5.5{\pm}0.2^{\circ}C$. Egg size was $1.5{\pm}0.03mm$. Six hours after fertilization the eggs were at the 2 cell stage, and the eggs hatched approximately 340 hours after collection. At hatching, larval length and yolk sac area were $5.2{\pm}0.25mm$ and $9.5{\pm}1.00mm^2$ (100%), respectively. Four days after hatching, the yolk sac area was $2.2{\pm}0.53mm^2$ ($23.1{\pm}5.55%$). This is the first report of collection of naturally fertilized eggs from pollock and their subsequent hatching while held in an indoor deep-sea water tank. The results suggest that such collection could assist in the recovery of pollock resources and the possibility of domestic rearing of cultivated larvae.

• 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.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.4 no.3_4
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• pp.113-120
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• 1971

In 1971, about 150,000 fingerlings of grass and silver carps were produced and distributed from the Fishculture Laboratory of Pusan fisheries College. The adults Were those transplanted from Japan in 1963. Findings during the process of this production are summarized as following : 1. Brood fish must be handled with a great care during the catching, hormone injection and maturity inspection so as the fish are not injured, otherwise, the eggs would not mature perfectly. Scale fall also affects significantly. 2. The amount of pituitary to be injected is preferable to be 2 to 3 times or more in donor's body weight to obtain good results. 3. The eggs should be spawned or stripped and inseminated as soon as mature. If the spawning is delayed the eggs become overmature and the hatching rate decreases significantly. 4. The water once used for the incubation of eggs should not be reused. The eggs under hatching process were melted away when water once used for incubation was reused. 5. A great care must be paid to keep water in quality when the net cage culture system is employed for raising fry or early fingerlings of Chinese carps. The best method to keep water in quality is to supply water in the cage continuously through a pipe or hose. 6. Heavy outbreaks of Spirogyra occured when clear well water was supplied into the cage, and a great number of fry or fingerlings were trapped or entangled resulting in a significant decrease of fish under rearing. It was prevented when moderately bloom-ed pond water was supplied into the cage. 7. Silver carp fry are usually captured and transported in the cool season because they can not be handled in the warm season owing to a high mortality, but cage cultured small size fingerlings ranging from 1.5 to 2 cm in total length are easily handled and transported even in the hot summer season, thus it enables the fish farmers to start growing them one season earlier.