• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.265-278
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• 2016

In this study, an ascending capability experiment was performed with largemouth bass and bluegill, which are exotic fish species inhabiting (the freshwaters) in Korea. The experiment was performed by dividing the subject fish into four groups according to their size and at four flow rates for each group. The number of fish passing through a reference line was analyzed by recording videos, and their swimming and ascending capabilities were observed by the naked eye. The number of fish passing through the reference line did not include those returning downstream within five minutes due to the high flow rate. The flow rate used for the analysis was the mean of the flow rate values measured at the left bank, the right bank, and in the middle of the stream. The results showed that the number of exotic fish migrating upstream decreased as the flow rate increased, regardless of the species and size of the fish. The comparison between the fish species showed that the ascending capability of bass was higher than that of bluegill, but the difference was not significant when considering the difference in the size of the fish. In addition, the upper limit flow velocity allowing the ascending of the exotic fish species was 1.11 m/s, when considering the fish returning to the downstream after the upstream migration and experimental error. The results of the experiment may be used as fundamental data for the blocking of fish and the management of exotic fish species by means of a high flow rate current. Further experiments, verification, and monitoring may need to be conducted continuously to determine whether the fish are able to pass through the reference line at a high flow rate, when they attain a high or cruising velocity. Additionally, the reaction of the fish species should be investigated by considering the response to external forces as well as pressure differences due to the flow rate.

• Journal of information and communication convergence engineering
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• v.18 no.2
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• pp.106-114
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• 2020

We propose appropriate criteria for obtaining fish species data and number of learning data, as well as for selecting the most appropriate convolutional neural network (CNN) to efficiently classify exotic invasive fish species for their extermination. The acquisition of large amounts of fish species data for CNN learning is subject to several constraints. To solve these problems, we acquired a large number of fish images for various fish species in a laboratory environment, rather than a natural environment. We then converted the obtained fish images into fish images acquired in different natural environments through simple image synthesis to obtain the image data of the fish species. We used the images of largemouth bass and bluegill captured at a pond as test data to confirm the effectiveness of the proposed method. In addition, to classify the exotic invasive fish species accurately, we evaluated the trained CNNs in terms of classification performance, processing time, and the number of data; consequently, we proposed a method to select the most effective CNN.

• Journal of Ecology and Environment
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• v.46 no.1
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• pp.41-53
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• 2022

Background: Due to the rapidly changing climatic conditions, South Korea faces the grand challenge of exotic species. With the increasing human movement, the influx of alien species to novel regions is prevalent across the globe. The latest research suggests that it is easy to prevent the introduction and establishment of alien species rather than controlling their spread and eradication. Like other countries, the Korean Ministry of Environment released a list (in 2018) of 45 potential risky exotic fish species considered likely to be invasive candidate fish species if they ever succeed in entering the Korean aquatic ecosystems. Results: The investigation into the invasion suitability traits showed that potential risky fish species could utilize those features in becoming invasive once they arrive in the Korean aquatic ecosystems. If the novel species establish viable populations, they are likely to incur higher economic costs, damage the native aquatic fauna and flora, and jeopardize the already perilled species. Furthermore, they can damage the installed infrastructure, decline overall abundance and biodiversity, and disturb the ecosystem services. Here we reviewed the list of fish species concerning their family, native origin, preferred aquatic biomes, main food items, current status in Korea, and potential threats to humans and the ecosystems. Data shows that most species are either already designated as invasive in the neighboring counties, including Japan, Vietnam, Thailand, and China, or originate from these countries. Such species have a higher climate match with the Korean territories. Conclusions: Therefore, it is exceptionally essential to study their most critical features and take regulatory measures to restrict their entry. The incoming fish species must be screened before letting them in the country in the future. The regulatory authorities must highlight the threatening traits of such species and strictly monitor their entrance. Detailed research is required to explore the other species, especially targeting the neighboring countries fish biodiversity, having demonstrated invasive features and matching the Korean climate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.390-397
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• 2017

The introduction of exotic fish species may reduce the number of native fish species and disturb the aquatic ecosystem. Therefore, measures to block and manage fish species are required. Accordingly, a fish species blocking system using bubbles was developed in this study to block exotic fish species. An experimental channel was produced and the possibility of blocking such exotic fish species was evaluated. The bubble generator is a system that produces a bubble curtain by generating air with an air compressor that blocks fish species. Bluegill, which is an exotic fish species in the country, was tested with this generator. The size of bluegill was between 0.10 m and 0.15 m and the depth of water was maintained at 0.70 m. The flow velocity of the experiment channel was classified into 3 levels (0.20 m/s, 0.10 m/s, and 0.05 m/s) considering the natatorial ability of the fish species. The results revealed that 70.07% of bluegill showed movements to swim upstream before applying the bubble, but it is considered that the ascending rate would be higher given that the fish species thinks downstream is a habitat and showed almost no movement. However, when the blocking facility was installed, most fish species showed movements to return to the downstream again by the bubble curtain, indicating a very high blocking effect. In particular, when the generating bubble was terminated, the fish species swam back to the upstream area very soon, so the fish species blocking effect using the bubble was excellent.

• Ecology and Resilient Infrastructure
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• v.10 no.4
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• pp.193-200
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• 2023

Influx of exotic fishes is the problem of fish management. The reason why interest on river environment was increased. Recently, River project was conducted to consider environmental function on the ecosystem and Eco-Diversity. Therefore, farmlands structure along the river was removed such as vinyl greenhouse. Daejeo ecological park was built in 4 River project. Daejeo ecological park have significance habitat for migratory birds and eco-diversity. In spite of nature river improvement, ecological system in river will be break down by exotic fishes. This study was conducted to investigate analyze the fish faun and prevailing species occupancy in Daejeo ecological park. This data will be used to make the management plan of exotic fishes in ecological park around Daejeo ecological park.

• Ecology and Resilient Infrastructure
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• v.10 no.4
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• pp.184-192
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• 2023

Influx of exotic fishes is the reason of destruction of the ecosystem and Eco-Diversity Recently, River project was conducted to consider environmental function. Therefore, farmlands structure along the river was removed such as vinyl greenhouse. In order to supply water eco-diversity, ecological park was built. In spite of nature river improvement, the ecological system in river will be break down by exotic fishes. This study was conducted to investigate analyze the fish faun and prevailing species occupancy in Nakdong river. This data will be used to make the management plan of exotic fishes in ecological park around Nakdong river.

• Journal of Environmental Impact Assessment
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• v.7 no.1
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• pp.23-34
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• 1998

This study was carried out to survey the fauna of some parks around Kunsan-city and to establish biological impact on the development of those parks. Among the fauna surveyed, insects consist of 74 species in 49 families and 13 orders. The insect fauna was poor, because the environment was made of simple flora and mostly farmland. Fish in the reservoir of Wolmyong-Park consist of 7 species. Among them, Ctenopharyngodon idellus is an exotic species and characterized with its voracious plantfeeding. This fish severely destroyed the habitats and spawning sites of other sympatric fish. For the conservation of non-exotic fish, birds, and mammals in the area, the integrated biological direction would be needed.

• Korean Journal of Ecology and Environment
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• v.40 no.4
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• pp.546-552
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• 2007

The objectives of this study were to analyze fish compositions, based on trophic guilds and tolerance guilds and determine community characteristics structure at five sampling sites of Yeongsan Lake during July 2006-May 2007. Total number of species sampled was 30 species and the number was 1350. Cyprinidae (77%) and Centrarchidae (15.7%) dominated the community and then followed by Cobitidae(2.7%), Gobiidae(2.4%), Mugilidae (0.5%), and others (0.1%). The relative abundance of tolerant and omnivore species at all sites was 63% and 77% of the total, respectively, suggesting an ecological degradations in the Lake. Exotics species such as large mouth bass (Micropterus salmoides), which is a top-carnivore in the water distributed at all sampling sites, implying that ecological disturbance was severe based on previous reference of US EPA (1991). Also, we found external anomalies such as external deformities, bleeding and tumors and not found migratory fish. Analysis of fish community structure showed that species diversity index and richness index was the highest in Site 1 and the dominance index was the highest in Site 2. In this study, high proportions of tolerant species and omnivore species, widespread exotic species, and frequent observations of abnormal fish. Such problems may be directly or indirectly associated with high nutrient enrichments and the reduced flow velocity by the dam construction. The ecosystem restoration by dam removal or removal of exotic top-carnivore fish may be one of the best strategies for better lak management.

• Asian-Australasian Journal of Animal Sciences
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• v.9 no.4
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• pp.389-396
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• 1996

In the first of two experiments, liveweight gain responses and carcass characteristics were investigated using two breeds of growing male goats, local (Dhofari) and exotic (Cashmere), fed on a whole pelleted-high fiber date by-products' based diet at 32.5% level (As-fed) supplemented with 12% fish (sardine), (HF-Fish) and a commercial concentrate diet (conc.). The (HF-Fish) diet was formulated to be iso-nitrogenous to the (conc.) diet, supplying 14% CP (DM-basis). Both diets together with Rhodes grass hay (Chloris Guyana) were fed ad libitum. The experimental design was a complete random arranged in a $2{\times}2$ factorial with breeds and diets as the main factors, using six animals per treatment. The experiment lasted for 84 days and goats were penned individually. At the end of the feeding trial, three animals from each treatment group were slaughtered for carcass evaluation. In experiment 2, diets' digestibility and N-balance were determined using 3 sheep per diet. The (HF-Fish) diet significantly(p < 0.05) improved liveweight gain. There was also a significant difference(p < 0.01) between breeds, with Cashmere gaining more than local goats. Feed conversion efficiency, dressing percent and longissimus dorsi area were not significantly affected by diet or breed(p > 0.05). Digestibility of the proximate components and N-balance for both diets were similar and not significantly different(p > 0.05). Fish supplementation greatly improved the digestibility of CF, ADF, NDF, cellulose and hemicellulose. Meat production ost was decreased by 31% due to feeding of the (HF-Fish) diet.

• Korean Journal of Environmental Biology
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• v.37 no.2
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• pp.177-188
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• 2019

The objective of this study was to analyze the distribution patterns of two exotic disturbing fish species (largemouth bass, Micropterus salmoides and bluegill, Lepomis macrochirus), their physical habitat features, and chemical water qualities from 13 sites of Dongjin River. The relationships between the fish distributions and water chemistry and physical habitat characteristics (i.e., bottom substrate) were evaluated by comparing dominant vs. absent regions of largemouth bass and bluegill. The relative abundance of the two species decreased sharply with decreased in the water quality in terms of BOD, PO₄-P and pH, but not with NO₃-N and conductivity. The bluegill showed no difference in habitat preference between the two regions with regard to the bottom structure, while the largemouth bass had significant differences in the bottom structures of silt, coarse gravels and boulders. The dominant species were Zacco platypus (14.6%), Lepomis macrochirus (14.0%), and Micropterus salmoides (9.8%) in the order of relative abundance, indicating that exotic species (24% in total) dominated the fish community, perhaps ensuing large ecological disturbances on the ecosystem. In conclusion, the results of this study suggest that the distribution of the two exotic species may be largely influenced by water quality of organic matter and nutrient pollutions.