• Parasites, Hosts and Diseases
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• v.62 no.1
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• pp.1-29
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• 2024

This article analyzed the infection characteristics of metacercariae of Metagonimus spp. (MsMc) in fish from 9 major water systems in Korea. A total of 19,568 fish in 87 species were examined over a period of 10 years (2011-2020). MsMc were detected in fish from all 44 survey areas in 9 water systems. Most of the surveyed sites showed very low and low infection levels (66.7%), while 33.3% of the areas, such as Tamjin-gang and Seomjin-gang, revealed moderate and high infection levels. High endemicity depends on the abundance of susceptible fish species, especially sweet smelt (Plecoglosus altivelis). The susceptibility index (SI) with MsMc in index fish, Zacco spp., was very low and low levels in 62.0%, moderate in 28.0%, and high in 10.0% regions. The SI was highest in the following order: Yeongam-cheon (283.8), Hoeng-cheon (192.3), Togyo-jeosuji (131.2), Deokcheon-gang (119.1), and Joyang-gang (106.3). The recent infection status of MsMc in P. altivelis was analyzed by the survey localities. In addition, except for P. altivelis, 9 fish species were highly infected with MsMc in some survey areas, including Zacco platypus, Z. koreanus, Z. temminckii, Opsariichthys uncirostris, Rhynchocypris oxycephalus, Carassius auratus, Acheilognathus rhombeus, Onchorhynchus masou, and Tribolodon hakonensis. In Korea, 74 fish species (15 families) are collectively listed as second intermediate hosts of Metagonimus spp. This review provides several novel characteristics of MsMc infection and clarifies the fish species of second intermediate host of Metagonimus spp. in this country.

• Korean Journal of Ecology and Environment
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• v.53 no.1
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• pp.63-72
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• 2020

In this study, to discuss on the applicability of eDNA as a new method to investigate fish diversity at streams, we applied eDNA at 4 streams (Geum River, Ji Stream, Hwangji Stream, Seomjin River), where endangered species are inhabits, with conventional survey (cast net and kick net). The average (±standard deviation) number of species investigated by eDNA were 19 species (±4.4), and it was relatively higher than average of conventional survey, 10 species (±4.8). Most of case, in this study, eDNA was more efficient than conventional survey. However, there were errors on species identification of Korean endemic species and aliied species from eDNA, and it seems the universal primer (MiFish primer set) is not suitable for them. Furthermore, some of endangered species, caught by conventional method, was not detected by eDNA. As the present universal primer is not suitable for identify the every freshwater fish species in Korea, the complementing or development of universal primer is needed, and the eDNA application after species specific marker development for detecting specific species like endangered species should be considered. In conclusion, if the manual for field survey method by eDNA is developed, we expect applicability enlargement for water ecosystem survey.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.1
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• pp.30-38
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• 2014

Hydro-acoustic survey was carried out to investigate the spatial characteristics of fish distribution near two artificial reefs (AO: large octagonal semi-sphere and AC: combined custom built) having different types in Jeju marine ranching area. The survey system consisted of scientific echo sounder (EK60), DGPS system, and ECDIS (Mecys). Field survey was conducted on August and October 2012 with star survey and line transect survey line method, and species composition was investigated from gill net fishing survey. The acoustic signals from individual fishes and small fish schools were mainly recorded around AO, but large and strong signals from large fish school were mainly detected in the top layer of and the water column near AC. The echogram suggest that the fish aggregation for the two types of AO and AC exist the significant difference in fish species and spatial distribution pattern.

• Ocean and Polar Research
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• v.41 no.1
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• pp.11-18
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• 2019

This acoustic experiment noted that fish species in Chilam-Gijang marine ranching area were more densely distributed in the pelagic zone during nighttime than daytime. In each season, the gill nets caught 15 different fish species and the estimated average target strengths were -44.0 dB and -44.4 dB for autumn and winter surveys, respectively. The estimated autumn fish biomass were 7.7 tons and 26.0 tons during daytime and nighttime, respectively. Winter biomass was 2.27 tons and 30.97 tons during daytime and nighttime, respectively. Different fish species form schools that exhibit different movements and behaviors, and thereby occupy varying water layers. These results explained the estimated fish biomass, and variation with seasons and time of the surveys around artificial reefs in Chilam Bay, Korea.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.2 no.4
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• pp.235-246
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• 2021

This study investigated the impact of baseflow on fish community in the Ungcheon stream (16.5 km long) located downstream of the Boryeong Dam, Korea. Based on field monitoring, there were five dominant fish species in the Ungcheon Stream accounting for 75% of the total fish community: Zacco platypus, Zacco koreanus, Tridentiger brevispinis, Rhinogobius brunneus, and Pungtungia herzi. These five fish species were selected as target species. HydroGeoSphere (HGS) and River2D models were used for hydrologic and hydraulic simulations, respectively. A habitat suitability index model was used to simulate fish habitat. To assess the impact of baseflow, each representative discharge was examined with or without baseflow. The HGS model was used to calculate baseflow within the study reach. This baseflow was observed to increase gradually with longitudinal distance. Validation of the hydraulic model dem onstrated that computed water surface elevated when baseflow was included, which was in good agreement with measured data, as opposed to the result when baseflow was excluded. Composite suitability index distributions and weighted usable area in the study reach were presented for target species. Simulations indicated that the baseflow significantly increased habitat suitability for the entire fish community. These results demonstrate that there should be a substantial focus on the baseflow for physical habitat simulation.

• International Journal of Advanced Culture Technology
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• v.11 no.2
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• pp.375-380
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• 2023

The study was conducted in Manu-stream, located in Paju, Gyeonggi-do, from January 2021 to December 2021. The survey points were selected in the upper and lower streams based on where thermal discharged to investigate water temperature and fish species and biological community analysis and growth rate were analyzed. The average annual water temperature difference between the upper and lower stream is about 11.0℃, and in the case of the lower stream area, the water temperature is maintained at 20.0℃ or more per year. Fish that appeared during the survey period decreased lower stream compared to the upper stream, which is believed to be the result of a decrease in temperature-sensitive species as the simple riverbed structure and water temperature increased compared to the upper stream. As a result of biological community analysis, it showed a relatively stable community state at the upper stream. The growth rate of fish has a high regression coefficient b value in lower streams throughout the four seasons. It showed relatively good growth lower stream, with a high water temperature. However, the results of each survey point are similar from season to season. The indicator species is a resistant intermediate species, and the range of resistance to water temperature is wide, so it is judged that water temperature's effect on the indicator species' growth is low.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.60 no.2
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• pp.128-141
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• 2024

Fish resource surveys were conducted near Jeju Island in June, August and October 2021 using an underwater camera monitoring system, fish pots, and SCUBA diving methods. The efficiency of the methods used to survey fish resources was compared using the number of individuals compared to area per unit time (inds/m³/h) and the number of species compared to area per unit time (spp./m³/h). As a result of comparing the number of individuals compared to the area per unit time (inds/m³/h), the order was underwater camera 214.69, SCUBA diving 124.62, and fish pots 0.57 inds/m³/h. The number of species compared to area per unit time (spp./m³/h) is in the following order: SCUBA diving 0.85, underwater camera 0.38, and fish pots 0.01 spp./m³/h. The fish resource monitoring method using underwater cameras was found to be more efficient in individual counts, and the SCUBA diving method was found to be more efficient in species counts. When considering cost and survey efficiency, the fish resource survey method using underwater cameras was judged to be more effective. The results of this study are expected to be widely used in estimating the population density of fish, which is the core of future fisheries resource surveys.

• Korean Journal of Environmental Biology
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• v.20 no.2
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• pp.152-157
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• 2002

The fauna of freshwater fish and the structure of fish community were investigated from March to October in 2001 at six stations in the middle reach of the Seomjin River, Gokseong-gun. The collected fishes (1,786 individuals) were identified into 30 species of 22 genera belonging to S families. Of them, cyprinid fish occupied 26 species, only one species (Rhinogobius brunneus) was secondary freshwater fish. Dominant species was Zacco platypus (dominance index: 24.2%) and subdominant species was Pungtungia herzi (10.7%). The endemic species of Korea were 11 species including Rhodeus uyekii (36.7%) about the ichthyofauna. In estimation of water quality by diversity indices, the general conditions of water quality of all survey times and all stations were relatively fine $(\beta$-mesosaprobic, diversity index: 2.70). But four survey sites except St. 2 and St. 3 showed severe water pollution with one or move times in total survey periods.

• Journal of Korean Society on Water Environment
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• v.24 no.2
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• pp.206-213
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• 2008

Fish fauna and community structure were investigated at 2003, 2004 and 2006 in Lake Paldang and its inflows. In this survey, we collected 54 species belong to 14 families. Family Cyprinidae take 51.9% (28 species), Cobitidae and Gobiidae occupied 7.4% (each 4 species), respectively. E. erythropterus (11.8%) was dominant species and L. macrochirus (10.2%), designated as an ecosystem-invasive alien fish species by Ministry of Environment, M. yaluensis (9.1%), Z. platypus (7.7%) and R. brunneus (6.7%) were dominated in turn. H. molitrix, C. lutheri, P. altivelis, S. microdorsalis, L. costata. S. gracilis majimae, A. rivularis, P. koreanus. S. scherzeri and O. platycephala were rare species (less than 0.1% in relative abundance). In-lake area, 36 species of fishes belonging to 11 families were collected, and 48 species of 13 families were from inflows. The number of Korean endemic species were 19 species (35.2%), and 4 kinds of exotic species (7.4%), that is, C. cuvieri, H. molitrix, L. macrochirus and M. salmoides were found at this survey area. It was revealed by the analysis of fish community that diversity and richness indices were prominent at tributaries, and dominance index was high at the main body of Lake Paldang. Fish fauna showed rapid decline after dam construction which make the mid-Han river systems to lentic ecosystem, so many of meander-riffle fishes were disappeared dramatically. But after 1990s when installation of small scale wastewater treatment plants started in watershed, the water quality of small tributaries was improved. And also, expansion of the natural macrophytic vegetation of littoral zone should contribute to the development of diverse fish fauna in Lake Paldang.

• Korean Journal of Ecology and Environment
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• v.43 no.4
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• pp.503-512
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• 2010

This study was conducted to evaluate fish fauna, species composition, and various guilds against stream orders along with analysis of fish community structure and diversity in Geum River watershed from 2005 to 2007. The total number of fish collected was 4,216 representing 12 families with 56 species. Zacco platypus was the most abundant fish species with 26% in relative abundance (RA). Korean endemic species were 24 species including Zacco koreanus, Microphysogobio yaluensis, Gobiobotia nakdongensis, and Iksookimia koreensis, etc. We also collected endangered fish species such as G. nakdongensis, Liobagrus obesus, and Pseudopungtungia nigra, etc., and their new distribution sites were found in the survey, providing some sites of the fish conservation and protection. Fish tolerance and trophic guilds analysis showed that the proportion of sensitive species, intermediate species, and tolerant species were 33.4%, 29.3%, and 37.3%, respectively and omnivores and insectivores were 48.1 % and 38.4%, respectively. Analysis of site-base study indicated that tolerant species and omnivore species were high in some polluted tributary streams (i.e., Gap and Miho stream) and sensitive and insectivore species were low. In the functional relations, expressed as simple linear regression equations, of stream order on fish metric attributes, showed that the number of species and the number of individuals increased as the stream order increases. This phenomenon was explained by greater availability of stable water volume, rich food, and higher physical habitat capacity. Such guild compositions and stream order characteristics of the river influenced the community structures, based on species diversity, dominance and evenness index in the study. This study may be used as important data in the future for comparisons of fish fauna and compositions before and after two weir (dam) constructions in the middle of Geum River by the government.