• Journal of Korean Society on Water Environment
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• v.31 no.3
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• pp.319-327
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• 2015

The present study was carried out to develop biological criteria for aquatic ecosystem health assessment using composition and diversity of collected species. The sampling sites were a total of 67 sites in the Han River (29 sites) and the Nakdong River (38 sites), May and September 2012. During the survey period fish were collected totally 93 species. In each water system, 73 and 61 species were collected in the Han River and the Nakdong River respectively. The current composition of fish species between the Han River and Nakdong River showed similar pattern. The dominant species was Zacco platypus of the Han River, and the Nakdong River was Opsariichthys uncirostris. In particular, ecological characteristics of O. uncirostris frequently appeared in general polluted waters. In conclusion, in the Nakdong River, average value of FAI (Fish Assessment Index) was averaged 41.3, indicating a "poor condition", and the Han River was 53.1, indicating a "poor condition". The aquatic health of the Nakdong River assessed based on FAI was considered to be worse than that of the Han River.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.59 no.4
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• pp.315-327
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• 2023

In the last five decades, there has been a consistent decline in the total catch of fisheries in the Korean jurisdiction since the peak in 1986. The decline in catch slowed and slightly rebounded in the 2000s, but changed back to a decline in the 2010s. As indicators that can identify changes in the marine ecosystem, trophic level (TL), biodiversity index (H'), and the ratio between pelagic fish and demersal fish (P/D) were analyzed by each local marine ecosystem. There were some different changes in each local marine ecosystem, but the mean TL and H' decreased and P/D increased in general in Korean waters. Demersal fish, which were dominant in the 1970s and 1980s, declined, and small pelagic fish and cephalopods have dominantly changed since the 1990s. However, these changes are not simple, and they are fluctuating in complex ways relating to each marine ecosystem and the timing. It is believed that changes in marine ecosystems in Korean waters are likely caused by a combination of fisheries and climate change. The ecosystem indicators reflected a change in the total catch, a sharp drop in catch of demersal fish, and increasing catch of pelagic fish since the mid-1980s.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.6
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• pp.505-510
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• 2004

The feeding habits of brown barracuda (Sphyraena pinguis) were analyzed using the stomach contents of monthly samples collected from coastal waters of Gadeok-do, Korea from January to December, 1998. Brown barracuda occurred mainly from summer to autumn in the study area, and ranged from 15 to 35 cm in standard length. Brown barracuda was a piscivorous fish which, mainly consumed teleost fish such as anchovy (Engranlis japonicus) and chefoo thryssa (Thfssa kammalensis). Its diet also included small quantities of shrimp and cephalopods. Although smaller fishes (<25 cm SL) consumed shrimp and cephalopods as well as fish, larger fishes (>30 cm SL) consumed exclusively teleost fish. The prey size increased with increase of fish size.

• Fisheries and Aquatic Sciences
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• v.11 no.1
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• pp.61-69
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• 2008

Using empirical data of fish performance and physiological limits as well as physical stimuli and environmental data, a cod-end selectivity model based on a chaotic behavior model using the psycho-hydraulic wheel and neural-network approach was established to predict fish escape or herding responses in trawl and cod-end designs. Fish responses in the cod-end were categorized as escape or herding reactions based on their relative positions and reactions to the net wall. Fish movements were regulated by three factors: escape time, a visual looming effect, and an index of body girth-mesh size. The model was applied to haddock in a North Sea bottom trawl including frequencies of movement components, swimming speed, angular velocity, distance to net wall, and the caught-fish ratio; simulation results were similar to field observations. The ratio of retained fish in the cod-end was limited to 37-95% by optomotor coefficient values of 0.3-1.0 and to 13-67% by looming coefficient values of 0.1-1.0. The selectivity curves generated by this model were sensitive to changes in mesh size, towing speed, mesh type, and mesh shape.

• Ecology and Resilient Infrastructure
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• v.4 no.2
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• pp.105-114
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• 2017

This study performed physical habitat simulation for fish and macroinvertebrate species in the Gongneung River. Target fishes were selected as Rhinogobius brunneus and Zacco platypus. Target macroinvertebrate species were selected as Hydropsyche kozhantschikovi and Chironomidae. Habitat suitability curves were constructed by using monitoring data from the monitoring project which is called "the survey and evaluation of aquatic ecosystem health". For calculation of CSI, weighted mean method was used. For macroinvertebrates species, the weighting factor derived from analytic hierarchy method was considered. River2D, which is capable to simulate flow in two-dimensional space, was selected for flow computation. Composite suitability index was simulated for target fish and macroinvertebrate species for discharge of drought, low, normal, and averaged-wet flow. Simulation results show that Chironomidae and Hydropsyche kozhantschikovi prefer the pool and riffle habitat, respectively. Rhinogobius brunneus and Zacco platypus show high suitability in riffle habitat.

• Journal of fish pathology
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• v.19 no.2
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• pp.173-181
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• 2006

Miamiensis avidus is a scuticociliate causing mortality in olive flounder Paralichthys olivaceus. To evaluate immune response of olive flounder against M. avidus, 2.6×106cells/fish of Formalin killed cell (FKC) was intraperitoneally (i.p.) injected, and 2.4 × 106cells/㎖ of sonicated FKC was immersion immunized to 14.9 cm (26.8g) fish. Fish were immunized 2 times with 2 weeks intervals. Antiserum from immunized fish caused agglutination and immobilization of the ciliate. In ELISA test, immunized group exhibited higher titers than control group. In addition, i.p. immunized fish showed higher phagocytic ratio, phahgocytic index and chemotaxic activity. To evaluate in vivo efficacy of FKC on fish, 1.43 × 105cells/fish was i.p.. injected, and 2.2 × 105 cells/㎖ of sonicated cell was immersed into 8.6cm (6.3g) fish. After 2 times immunization with 2 weeks intervals, fish were infected with 2.0 × 104 and 2.0 × 103 cells/ml of live ciliates by immersion. After 3 weeks, cumulative mortality was lower in the i.p. immunized group and mortality was delayed in immersion immunized group. In conclusion, specific immune response of oliver flounder against M. avidus was elevated after immunization and these immune response may prevent and/or delay for the M. avidus infection to olive flounder.

• Korean Journal of Ecology and Environment
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• v.40 no.1
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• pp.103-109
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• 2007

To investigate the effects of artificial vegetation island (AVI) on fish distribution, we compared fish fauna from artificial vegetation island (AVI) area, which installed in 2000, natural vegetation area (NVA) and vegetation-free area (VFA) at Kyungan Stream area of Lake Paldang from Jul. to Nov., 2005. Results showed that 11 families 23 genera 24 fish species were distributed in the AVI and NVA. Squalidus japonicus coreanus, a small-size fish which generally lives at the downstream, dominated absolutely in the individual numbers. However, only 6 families 11 genera 12 species of fishes caught at the VFA, and dominant fishes were Hemibarbus labeo and Erythroculter erythropterus, a medium to large-size migratory fishes which live in mid-depth of water column. The dominance index was high at the AVI (0.778) and NVA (0.868), whereas the diversity index and evenness index were high at the VFA. Fish distribution at AVI was similar to that of the NVA in numbers of species, indicating that the AVI could playa role as spawning and inhabitation zone to a variety of fishes. We believe that AVI may be used for a restoration of the damaged and disturbed littoral ecosystem.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.2B
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• pp.193-203
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• 2011

With the recent growth of environmental and ecological interests, various river restoration and habitat environment creation projects are being carried out. For this, the estimation of the habitat flow discharge is important. In U.S. and Europe nations, The instream flow incremental methodology (IFIM) has been used to estimate the habitat discharge. IFIM is the method that can be applied to evaluate the flow discharge for the suitable habitat. To use the IFIM in river, a habitat suitability index(HSI) for the target organism is needed. However, HSIs for only two species of Zacco platypus and Zacco temminckii were proposed from the field monitoring. Thus, for the estimation of the ecological flow rate for a group of fish, the development of the HSIs for various fish are necessary. In this study, physical data such as water level and flow rate, chemical data such as acidity and dissolved oxygen, and life data such as fish types and population are collected in Keum river watershed. Based on the 2,736 field data, HSIs for the following 6 fish are developed: Zacco platypus, Zacco temminckii, Microphysogobio yaluensis, Coreoleuciscus splendidus, Pungtungia herzi, Pseudogobio esocinus. Through the comparison with HSIs in the literature, the developed HSIs are modified. Also, the limits of Froude number, pH, and DO for 6 fish are proposed. The HSIs developed in this study can be utilized as a essential data for performing river project evaluations.

• Fisheries and Aquatic Sciences
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• v.5 no.2
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• pp.122-126
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• 2002

A feeding trial was conducted to determine compensatory growth of juvenile olive flounder in the spring. Five treatments of fish with 3 replicates were prepared: the control group fish (C) fed twice daily for 8 weeks, the Sl, S2, S3 and S4 fish fed for 7, 6, 5 and 4 weeks after 1, 2, 3 and 4 weeks of starvation, respectively. Survival of olive flounder was not significantly different among treatments. Weight gain of flounder in S2 was significantly (P<0.05) higher than that of fish in S3 or S4, but not significantly different from that of fish in C or Sl. The poorest weight gain was observed in fish of S4 treatment. Specific growth rate (SGR) for flounder in S2 was significantly (P<0.05) higher than that for fish in C or S4, but not significantly different from that of fish in Sl or S3. Feed intake (g/fish) was proportional to duration of days of feeding except for flounder in S2, but not significantly different among C, Sl or S2. Feed efficiency ratio (FER) and protein efficiency ratio (PER) for flounder in S2 were significantly (P<0.05) higher than for fish in C, but not significantly different from those for fish in Sl, S3 or S4. Hepatosomatic index (HSI) and condition factor (CF) for flounder in Sl, S3 and S4 were not significantly different from those for fish in C, but significantly (P<0.05) lower than S2 except for CF in Sl at the end of the experiment. Proximate composition of the whole body of flounder was not significantly different among treatments. In considering results of the experiment, juvenile olive flounder achieved compensatory growth when properly fed after starved up to 2 weeks in the spring. Compensatory growth of fish was supported by improvement in SGR, FER and PER in fish starved.

• Korean Journal of Ecology and Environment
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• v.42 no.3
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• pp.280-289
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• 2009

The fish communities and physical habitat conditions of fifteen tributaries of Lake Paldang in spring and autumn, 2008 were surveyed to evaluate the ecological health of the streams. The total 2,746 individuals were collected belonging to 11 families 31 genera 40 species. Two new species (Cottus koreanus, Gnathopogon strigaus) that have never been reported as yet in Lake Paldang watershed were found for the first time. The most dominant species in the tributaries was Acheilognathus yamatsutae (19.9%) which is Korean endemic species. Ecological health evaluation of fifteen tributaries using index of biological integrity (IBI) model for fish community and qualitative habitat evaluation index (QHEI) was performed. According th the IBI analysis, four streams (Siwoo-Stream, Jojong-Stream, Moonho-Stream and Mugab-Stream) were evaluated as "good" condition (B grade), Woosan-Stream were "poor" condition (D grade) and others were "fair" condition (C grade). Qualitative habitat evaluation index values of the four streams were the grade "II" indicating "good" condition and those of eleven streams were the grade "III", indicating 'fair' condition. On the whole, dataset of IBI and QHEI showed that ecological health of Jojong-Stream has been well maintained compared to other tributaries of Lake Paldang.