• Korean Journal of Ichthyology
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• v.6 no.1
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• pp.39-50
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• 1994

Spawning of the bitterling, Acheilognathus yamatsutae into the mussel was studied from 1990 to 1992 in Lake Uiam, Korea. This fish preferred to spawn in certain mussel species such as Unio douglasiae, U. douglasiae sinuolatus, Lamprotula gottsehei and Anodonta arcaeformis flavotincta in order of preference. Within the same species of mussel, they preferred the larger size. Eggs and larvae were commonly located in the inner demibranch of mussels. Average number of eggs or larvae per mussel was 3.6(ranged from 1 to 35). The eggs of the bitterling were hatched out within 41 hours when water temperature remained over $20^{\circ}C$ and the larvae already possessed minute tubercles on the skin and yolk projections to prevent themselves being washed out from mussels.

• Fisheries and Aquatic Sciences
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• v.14 no.1
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• pp.55-61
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• 2011

Fish larvae were collected monthly with an ichthyoplankton net from 18 stations (including four stations located in eelgrass beds) in Gamak Bay and Yeoja Bay, southern Korea, in 2007. In total, 33 species of fish larvae were collected, of which Engraulis japonicus (48.5%), Tridentiger trigonocephalus (21.5%), and Omobranchus elegans (9.2%) were dominant. Dominant species varied seasonally: Hexagrammos otakii during December and January, Pholis nebulosa during January and March, Acanthogobius flavimanus in April, T. trigonocephalus in May, E. japonicus during June, July, September, and November, and Sillago japonica in August. Dominant species also differed between sites inside and outside the bays. Leiognathus nuchalis, O. elegans, and T. trigonocephalus were more abundant inside, while H. otakii was more abundant outside. From cluster analysis, three groups were identified according to sampling months (January-April, May-September, and October-December) and two groups according to station (inside and outside bays). The occurrence of small larvae of almost all major fish species indicated that the bays were used as spawning and nursery grounds. An exception was Lateolabrax japonicus, whose specimens were relatively large (>19 mm TL), suggesting that this fish may spawn offshore, with its juveniles approaching the bays with growth.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.5
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• pp.654-658
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• 2014

We report the first identification of a spawning ground of the blackfin flounder Glyptocephlaus stelleri near the Wangdol-cho sea mountains, located in the southern East Sea. Eggs and larval fish of G. stelleri were collected during April and June, 2014, when an abundance of eggs was found in the southern area of Wangdol-cho. Our findings suggest that G. stelleri prefers to spawn in the vicinity of the off-shore sea mountains, where the temperature is between 10 and $12^{\circ}C$ and the water depth is 100 m, rather than inshore.

• Journal of Environmental Science International
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• v.20 no.4
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• pp.551-554
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• 2011

The production of the sharp-toothed eel by commercial catch off waters of Korea is annually declined after 1978. This study was carried out to obtain the stock management of the sharp-toothed eel using the PCR-aided RFLP method. The mtDNA COI gene was amplified using species-specific primers and PCR product was observed to 700 bp. Amplified DNA fragments were treated with six kinds of restriction enzymes (BaeHI, EcoRI, PstI, Ksp22, HinfI and HaeIII). The treatment of HaeIII showed a distinct PCR product between Yeosu/Jinhae/Jeju/Goseoung and Jangheung/Haenam populations that were observed from 300 to 400 bp in reference to 100 bp molecular marker. However, DNA fragment within populations had an identical pattern. The phylogenetic homology is 82% between two populations inferred from RFLP PCR product pattern using NTsysPC ver. 2.1. The use of HaeIII plays an important role in discriminating populations. It is thought that adults after over-wintering in the southern part of Jeju migrate to the Yeosu, Jinhae and Goseoung regions to spawn instead of to southwestern waters. Individuals within populations showed a relatively active genetic mixing and migration regardless of geography. However, the genetic ancestor of Jangheung and Haenam populations is appeared to be more adjacent to China or Japan than Jeju.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.11a
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• pp.198-203
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• 2003

The effects of salmon carcasses on forest and stream ecosystems were determined by nitrogen stable isotope analysis in natural streams in Hokkaido, Northern Japan, where numerous chum salmon (Oncoryhncus keta) were migrated upstream ITom ocean to spawn in autumn. The leaves and soils surrounding riparian forest and stream dwelling invertebrates were collected before and after migration. The nitrogen stable isotope ratio $({\delta}^{15}N)$ of riparian vegetation (Salix spp.) were different depending on the presence of salmon and distance from the stream. The $({\delta}^{15}N)$ of stream dwelling invertebrates were different between salmon present and absent stream. This difference was tested using the experiment channel by implanting salmon carcasses. The nitrogen stable isotope ratio of epilithic algae and leaf shredding animals were nearly 3 higher in the salmon implanted treatment suggesting that around 20％ of salmon derived nitrogen was uptake either in algae and leaf shredding invertebrates. These results suggest that the salmon carcasses effects not only on stream primary production but also on primary consumers, which decompose leaves fertilized with nitrogen from carcasses.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.2
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• pp.145-150
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• 2014

This study investigates the preparation of anti-reflective (AR) coating film to improve the efficiency of solar cell. The AR coating film was successfully obtained by dip-coating with AR coatings prepared by sol-gel method. Fluoroalkylsilane was additionally introduced into the coatings to give the self-cleaning effect of AR coating film. We performed the abrasion test, pencil scratch hardness test and cross-cut test to identify the mechanical strength of AR coating film. As the results, the transmittance of AR coating films with 9.07, 18.13 and 27.20 of IPA/MTMS molar ratios were 93.1, 93.6 and 95.3%, respectively. The water contact angle and transmittance of AR coating film increased by the introduction of hydrophobicity. The prepared AR coating film shows the high level of abrasion, hardness and adhesion. The IPA/MTMS molar ratio of 27.20 and the withdrawing speed range of 0.20 ~ 0.28cm/sec are the optimal coating condition in terms of the transmittance and mechanical strength of AR coating film.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2003.10a
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• pp.158-158
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• 2003

Bioassays using gametes of sea urchins are widely used in ecotoxicological assessments of marine environments. Since most of sea urchin species in Korean coastal water spawn from spring to autumn, bioassay with them during the winter is impossible. In the course of developing standard methods for bioassays with Korean species, we found a winter-spawning starfish, Asterias amurensis, Since reproductive mode of asteroids is similar to echinoids, the bioassay protocol for sea urchins could be applied similarly to the starfish. Here, we tested and determined several conditions for the acceptability of bioassay with A. amurensis. The least required time for formation of fertilization membrane of fertilized eggs to be easily distinguished from unfertilized ones was 60 min. The threshold of sperm to egg ratio that could make acceptable fertilization rates in controls was 3000. The allowed time for manipulation of sperm after dilution in seawater was at most 3 hr. The optimal exposure time of sperms when the response against toxicant solution was relatively stable was in the range of 20-60 min. The tolerance range of sperms to the salinity of test solution was 26-38 psu. The sensitivity of A. amurensis sperm was intermediate among marine organisms commonly used in aquatic toxicity tests. The sperm bioassay with A. amurensis can be satisfactorily applied to toxicity assessments of marine environments.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.48 no.2
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• pp.118-127
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• 2012

The reproductive ecology of the glowbelly, $Acropoma$ $japonicum$ was examined using 637 specimens collected monthly from January to December 2006 in the coastal waters off Gori, Korea. The specimens ranged in standard length (cm, SL) from 2.9 to 11.4cm for female, 2.7 to 10.5cm for male. The gonadosomatic index (GSI) of female was highest in September and decreased until December, and the spawning season lasted from August to November. The monthly sex was not different significantly ($x^2$-test, p>0.05). The size at 50% maturity was estimated at 6.0cm SL. $A.$ $japonicum$ was multiple spawner that spawn on more than one occasion in a single spawning season, and the maximum egg diameter was 0.75mm. Fecundity (F) ranged from 12,052 to 104,246 eggs, with the mean of 38,321 eggs. The relationships between fecundity and standard length (cm, SL), body weight (g, BW) were estimated as $F=86.278SL^{2.9652}$ ($R^2$=0.7970) and $F=3036BW^{1.0081}$ ($R^2$=0.7992), respectively.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.52 no.4
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• pp.386-393
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• 2016

It is essential to provide good environment for juvenile fish to grow and spawn in order to keep reproduction mechanism of fisheries resources. However, harvesting juvenile fish deprives adult fish of the opportunity to reproduce, thereby changing self-regulating renewable resources into non-renewable ones and preventing sustainable harvesting as well as reducing fishers' income. We reviewed the catch status of Korea on juvenile mackerel and analyzed how reducing the catch ratio of juvenile mackerel may affect the spawning stock and Korean fishermen's revenue. In addition, we analyzed the problem of caching juvenile mackerel in Korean fisheries and current efforts to protect and reduce the catch ratio of juvenile mackerel in Korea. Furthermore, we suggested future efforts to protect juvenile mackerel. The result of the study showed that reducing the catch ratio of juvenile mackerel from 44.4% to 30.0% would increase fishers' revenue by 60.6 billion KRW. We suggest the changing of purse seine fishery's catching methods from night operation to day operation, relocation of fishing vessels to move to other fishing grounds when fishing vessels meet high density of juvenile mackerel, and consumers' clever choice of consuming adult mackerel in order to accelerate the move toward protecting juvenile mackerel in Korea.

• Journal of Aquaculture
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• v.21 no.3
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• pp.146-156
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• 2008

Tributyltin chloride(TBTCl) was administered through discrete immersion(2 hr each) from the $18^{th}-25^{th}$ day after hatching(dph). At the doses of 1, 2, 4 and 8 ${\mu}g/L$, the immersion at 2 ${\mu}g/L$ ensured 93% masculinization and the highest survival of 75% after the treatment. TBTCl acted as a growth suppressant and the magnitude of its suppression was stronger in females. During the 300 day experiment, it postponed sexual maturity of females from 120$^{th}$ dph in the control to 240$^{th}$ dph in the females treated at 8 ${\mu}g/L$. It reduced spawning frequency(22-3 times) and cumulative fecundity(1,632-19 eggs) by reducing the number of vitellogenic eggs. In the treated males too, it reduced sperm motility(100-68 sec); consequently, fertilizability of the sperm cells drawn from these males was also reduced from 88 to 43%. Progeny testing showed that the cross between males treated at>2 ${\mu}g/L$ and normal females generated the presumed 'homogametic' males. Both the treated 'homogametic' and 'heterogametic' males could induce the females to spawn fewer eggs than that of the normal males. A normal female somehow deducted the differences between the control, treated and sex reversed males; it preferred a normal male over a treated one, and a treated one over the sex reversed male.