• Korean Journal of Environment and Ecology
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• v.21 no.6
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• pp.506-514
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• 2007

Temporal and spatial distribution of fish community were investigated from September 2006 to April 2007 targeting the lagoon Youngrang, Korea. A total of 32 species belonging to 16 families were collected during the period, among which the species of primary freshwater fish accounted for 11 (34.38%), the species of peripheral freshwater fish for 18 (56.25%), and that of marine fish for 3 (9.38%) in collected fish community. As a result of taking a look at the transitional aspects of community by each surveyed station and period, it was found that when the 'Breaking-sandbar' occurred, there came a change in the composition ratio of the fish species according to their ecological characteristics. In addition, compared with the data obtained in the past with respect to the ichthyofauna of the lagoon Youngrang, it was found that the ratio of the primary freshwater species gradually decreased, while the peripheral freshwater and seawater species gradually increased according to the indraft of seawater. Thus, it was concluded that fish community in the lagoon seemed to go under transition in its spatio-temporal characteristics depending on the 'Breaking- sandbar.'

• Korean Aquaculture
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• v.14 no.1
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• pp.63-66
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• 2002

담수산 rotifer, Brachionus calyciflorus는 담수어류의 종묘생산시 초기 자어의 먹이생물로 많이 이용되고 있다. 특히, 이 종의 암컷은 수컷에 관계없이 암컷이 난을 생산하는 처녀생식과 수컷과의 교미에 의해 암컷이 수정란(내구란)을 형성하는 유성생식으로 나뉘어진다. 한편, 유성생식에 의해 형성된 내구란은 두터운 2차 난막으로 싸여져 있어 외부환경이 부화에 적합하지 않으면 강한 내구성을 지니고 있어 휴면 상태를 계속 유지한다. 이러한 내구란은 종의 유전적 형질을 효율적으로 보관할 수 있을 뿐만 아니라 대량배양하기 위한 종자 및 수산 생태 독성학의 실험재료로 이용할 수 있다. 또한 내구란은 Artemia cyst처럼 쉽게 부화시켜 자어에 직접 먹이로 공급할 수 있는 장점으로 인해 rotifer 대량배양에서 오는 유해 세균과 원생동물에 의한 자치어의 2차 감염을 방지 할 수 있다. 이처럼 rotifer, B. calyciflorus 내구란은 여러 가지 용도로 이용 가능하기 때문에 내구란을 대량생산할 수 있는 조건을 규명하는 것도 중요하다. 그리고 생산된 내구란을 사용 목적에 따라서 간편하게 이용하기 위해서는 내구란을 제품으로 만드는 것도 매우 중요하다. 따라서 본 내용은 담수산 rotifer 내구란을 상품화하기 위한 방법으로 내구란의 대량생산과 보존방법에 대해서 설명하고자 한다.

• Journal of Aquaculture
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• v.19 no.1
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• pp.14-18
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• 2006

The objective of this study was to evaluate food value and profitability of black porgy (Acanthopagrus schlegeli) cultured in freshwater. In fish flesh, muscular hardness of black porgy reared in freshwater $(9210{\pm}1215g/cm^2)$ was slightly lower than those of fish in seawater $(9987{\pm}6549g/cm^2)$, but there was no significant difference. Also, there was no difference between muscular strength of fish reared in freshwater and seawater. When the flesh qualities of black porgy reared in freshwater was compared with those of fish reared in seawater through the questionnaire, there were no significant differences between fish reared in freshwater and seawater in appearance, texture, taste and flavor. For 10 months of black porgy culture in fresh water, the gross profit in culturing from juvenile (5.5 g) to adult size (100g), and from adult to marketable size (400 g) were 24,000,000 won (30.0%) and 53,870,000 won (36.9%), respectively.

• Korean Journal of Ichthyology
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• v.24 no.3
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• pp.201-219
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• 2012

The estuaries bank of Nakdong River, Korea, was constructed in 1987 and many arguments have been under discussion on the subject of ecological impact on ecosystem during 20 years. In this context, however, it was not focused on the role of fish-way and the way of improvement to promote fish movement to complete its life history. This paper was the result of investigation on fish fauna of upper and lower part of the bank and the analysis of comparison of the fishes with those using fish-way which were installed in each side of bank as ladder type and fish gate. The authors discussed the importance of fish gate and its management base on the result. The number of fishes collected in this study for upper part of estuaries bank was 31 species, among them 71% was the pure freshwater residents indicating the characteristics of the area as a freshwater ecosystem. It was observed that 9 species of coastal fishes were found in this region including Coilia ectens and Neosalanx sp. which is anadromous to spawn. Excluding 6 freshwater fishes, 30 fish species collected in lower part of estuaries bank were coastal fishes indicating that former brackish ecosystem was changed into marine one. The freshwater fishes found in this region were restricted the appearance only in the season of discharging freshwater into the sea. The number of fishes found in fish-way was 39 species, more than that of river and coast. But only 19 species founded in fish ladder was comparable with the result of investigation on fish gate including 32 species. It was considered that the fish gate has more important role as a fish passage from the fact that only it allowed to movement of numerous number of fry of Neosalanx sp. and Engraulis japonicus. These results indicates that two-way movement system is more efficient than downward only one in estuaries bank for fish migration.

• Journal of Life Science
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• v.8 no.5
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• pp.589-597
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• 1998

In order to effectively utilize marine processing by-product such as fish scale, chemical compositions for the scale were analyzed. The selected fishes were gray mullet, Mugil cephalus, living in the sea and carp, Cyprinus carpio in the fresh water, having a lot of scales among the fishes living in seawater and fresh water. And we also investigated the difference in the chemical compositions between gray mullet and carp, depending on both living circumstances. The major components of the scales were found to be crude ash and crude protein which were each about 49% for gray mullet and which were about 20% and 79% for carp, respectively, on the basis of dried scales. The proteins extracted from both scales proved to be collagen through amino acid compositions and SDS polyacrylamide gel electrophoretic patterm. Also this scale collagen was assumed to by Type I collagen because the migration rate of $\alpha$1 and $\alpha$2 subunit of the collagen were almost the same those as calf skin Type I collagen. Most of proteins from gray mullet was collagen, however, the collagen content in proteins from carp was estimated to be only about 53%, on the basis of the ratio of hydroxyproline to protein. The crude ashes of both scales identified to be hydroxyapatite through element compositions and X-ray diffraction analysis. In conclusion, both fishes in different living circumstances were almost similar to in the chemical compositions but chemical contents for crude ash and crude protein.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.13 no.3
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• pp.109-113
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• 1980

Organic bases in the dorsal meat of wild common carp, Cyprinus carpio, were analyzed as a part of the studies on the taste compounds of fresh-water fishes. The male and female meat showed no significant differences in contents of total creatinine, betaine, TMA and TMAO. The most abundant basic compound was total creatinine $(ca.\;400mg\%)$. The amount of betaine was poor $(ca.\;66.5mg\%)$ and TMA and TMAO were trace in content $(below\;1mg\%)$.

• Journal of Life Science
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• v.30 no.12
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• pp.1063-1069
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• 2020

Two crucian carp species (Carassius auratus and C. cuvieri) inhabit Lake Yedang in South Korea, and C. auratus is known to be native to Korea. Classification of these two freshwater fish species is often confused because of their morphological similarity. To distinguish the two species, we conducted phylogenetic and population genetic analyses of C. auratus and C. cuvieri based on their mitochondrial DNA sequences of the cytochrome b gene (CYTB). We also compared our partial CYTB sequence (<1,056 bp) with 10 Chinese, nine Japanese, and two Russian crucian carp fishes. The results of our phylogenetic analysis showed that C. auratus and C. cuvieri were clearly divided into two phylogroups. The nucleotide diversity (π) of C. auratus from Korea, China, and Japan showed a range of 0.146%~0.421%, while the range of π of C. cuvieri from Korea and Japan was lower than those of C. auratus (0.0%~0.054%). Moreover, the comparison of CYTB divergence among crucian carp fishes in China, Japan, and Korea indicated that Korean Carassius fishes were distantly related to those from China and Japan, with two exceptions: the pairwise Fst value between Korean C. auratus and northern Chinese C. auratus was not significantly different. In addition, no significant genetic divergence between Korean and Japanese C. cuvieri was detected. We conclude that, despite the morphological similarities, C. auratus and C. cuvieri should be considered as separate freshwater fish resources in conservation efforts for genetic diversity.

• Journal of fish pathology
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• v.20 no.3
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• pp.249-255
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• 2007

We investigated the phenotypic characteristics by using API20E, APIZYM and determined minimum inhibitory concentrations (MICs) of 7 antibiotics in motile aeromonads isolated from freshwater fishes in Korea and Japan, and 4 American Type Culture Collection (ATCC) strains. All isolates (n=7) were identified as motile Aeromonas species according to API20E test. Lysine decarboxylase activity and acid production from 4 different carbohydrates including mannitol, rhamnose, amygdalin and arabinose were observed in various strains. In enzymatic activities by APIZYM, all isolates showed negative reactions in valine and cystine arylamidases, α-chymotrypsin, α-galactosidase, β-glucuronidase, α-glucosidase, α-mannosidase and α-fucosidase. Although the intensities of each enzymatic activity were diverse in alkaline phosphatase, esterase-lipase, leucine arylamidase, β-galactosidase and N-acetyl-β-glucosaminidase, all isolates showed positive reactions. All isolates were resistant to ampicillin sodium (MIC>100㎍/ml), but sensitive to chloramphenicol (MIC≤1.6㎍/ml). However, recently isolated strains (AC9804, AC0202 and GMA0361) were commonly resistant to tetracycline (MIC=50㎍/ml). Furthermore, AC9804 was resistant to oxolinic acid (MIC=12.5㎍/ml). GMA0361 was resistant to kanamycin sulfate (MIC>100㎍/ml) and streptomycin sulfate (MIC>100 ㎍/ml).

• Korean Journal of Environmental Biology
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• v.31 no.4
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• pp.411-418
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• 2013

The Saemangeum Reservoir was constructed in 2006 as a part of Saemangeum reclamation project in which desalination has been also carried out. The purpose of this study is to provide basic data for predicting changes in fish distribution in the Saemangeum area with respect to the desalination processand to identify current status of fish distribution along with salinity levels. Fish sampling and measurement of salinity were conducted 4 times from February to October in 2012 at 10 sites within the Saemangeum Reservoir. A total of 71 species classified into 34 families were confirmed, and dominant and subdominant species were Thryssa kammalensis (16.1%) and Konosirus punctatus (12.8%), respectively. Saltwater fishes were still dominant at the Saemangeum Reservoir. Study sites were classified into four groups (A=St. 1, 6; B=St. 2, 3, 7, 8; C=St. 4, 9, 10; D=St. 5) by Bray-Curtis cluster analysis. Species composition of each group was closely related with salinity level: group A corresponding to 0.2 psu, B to 14.2 psu, C to 19.5 psu, and D to 23.5 psu.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.2
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• pp.121-124
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• 2007

Freshwater-adapted maturing chum salmon (Oncorhynchus keta) involuntarily captured by stationary nets in Yang-yang seashore areas were transferred to freshwater in an outdoor raceway tank at Yeongdong Inland Fisheries Research Institute, NFRDI, Yang-yang, Gangwon, Korea and kept over 1 day until the start of the experiments. The freshwater-adapted females were single-injected intraperitoneally with gonadotropin-releasing hormone analogue, (GnRH-a: $70\;{\mu}g/kg$ body weight, BW) alone or combined with a dopamine receptor antagonist, pimozide($700\;{\mu}g/kg$ BW). Although gonadosomatic indices [GSI, (gonad weight/BW)${\times}100$] did not show significant changes in both 2004 and 2005, GSI of GnRH-a-injected fish during the 2005 trial slightly increased on the 5th and 7th days post-injection compared to those of vehicle treated fish. Hepatosomatic indices [HSI, (liver weight/BW)${\times}100$] of fish injected with GnRH-a alone and combined with pimozide decreased significantly on the 7th day post-injection in 2004(P<0.05). In 2005 trials, HSI was significantly reduced in GnRH-a treated fish on the 7th day post-injection (P<0.05). Pimozide-injected fish showed a pattern with increase of GSI and decrease of HSI, without significant differences. Taken together, these results suggest that at least in part hypothalamic hormones and dopamine receptor antagonist may induce sexual maturation in freshwater-adapted maturing chum salmon. It remains to evaluate these preliminary results by further researches.