• Korean Journal of Ecology and Environment
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• v.41 no.3
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• pp.301-310
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• 2008

This study was to analyze characteristics of fish compositions and longitudinal distribution, based on trophic and tolerance guild at 22 sampling sites of Yeongsan River watershed during 2003$\sim$2006, and also to compare before and after the estuary dam construction. The collected fishes, based on catch per unit effort (CPUE), were 44 species in the watershed and dominant fishes were Zacco platypus, Acheilognathus macropeterus, Zacco temminckii and Carassius auratus. According to comparative analysis of fish in the non polluted sites (NPS) vs. polluted sites (PS), the number of species and individuals was lower by 70% in the PS than the NPS, indicating ecological degradations by chemical pollutions or/and habitat modifications. The relative abundance of sensitive and insectivore species decreased as the stream order increases, while tolerant and omnivore species increased with the stream order. In this survey, largemouth bass (Micropterus salmoides), which is a top-carnivore and exotic species, may influence trophic guild system throughout active predations on endemic species, resulting in modifications of ecological functions. The construction of estuary dam on Yeongsan River in 1981 resulted in wider lacustrine zone and desalinated through limitation of seawater input. These physical changes have caused increases of lentic dwelling species and limited fish migrations (i.e., eel). Overall, fish fauna and composition analyses showed that the number of species and individuals in this water body may be reduced due to inputs of pollutants from the watershed, habitat modifications, and increases of exotic species (largemouth bass). For these reasons, effective lake management strategies are required for the ecosystem conservation.

• Journal of Aquaculture
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• v.20 no.1
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• pp.41-46
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• 2007

Seahorse is an interesting organism for the study of its conservation as well as development as an marine ornament fish. To investigate the ecological characteristics and fish fauna around the habitat of such an endangered species, fishes were collected from the seahorse habitat. A total of 161 fishes were classified into 8 families and 11 species including two species of seahorse, Hippocampus mohnikei and H. coronatus representing 1.9% and 1.2%, respectively, of the population. The most dominant fish species in the area was Takifugu niphobles accounting for 30.4% of the population. The predators of the seahorse such as Acanthopagrus schlegeli, Lateolabrax japonicus and Lateolabrax maculatus were found in the relative abundance of 0.6%, 5.6%, and 11.8%, respectively. The relative abundance of H. coronatus ($0.96\;ind./1,000\;m^2$), H. mohnikei ($0.97\;ind./1,000\;m^2$) and the other coexisting fishes are similar in all the areas investigated (P>0.05).

• Korean Journal of Environment and Ecology
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• v.30 no.6
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• pp.986-995
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• 2016

The objective of this study was to analyze the distribution of endangered fish species and elucidate their relations on chemical water quality, physical habitat conditions and ecological stream health. The dominant species in the watershed was Pseudopungtungia nigra (Pn), Gobiobotia macrocephala (Gm), Gobiobotia brevibarba (Gb), Liobagrus obesus (Lo), and Iksookimia choii (Ic) in the order. The species of Pn designated as "critical endangered species (I) (CER)", was most widely distributed species among the endangered species, so the designation of the species should be re-evaluated. The endangered species was most popular (4 species, 384 individuals) in the Cho-River region of eighteen lotic regions. According to the analysis of chemical tolerance limits in the habitats with endangered fish species, biological oxygen demand (BOD) and total phosphorus (TP) was analyzed as "very good" (Ia) and "good condition" in the chemical criteria of the Ministry of Environment, Korea. Also, chemical conditions, based on ammonia-N ($NH_{4+}$), total nitrogen (TN), phosphate-P ($PO_{4^-}P$) were much better in the habitat with endangered species (Hw) than the habitat without endangered species (Ho). In the meantime, the species of Ic showed wide ranges on the chemical tolerance, so physical habitat conditions, such as the size of substrate particles (sand) and hydrological regime, were considered as more important factors than the chemical water quality, if the water quality is not largely degraded. The endangered species were also more distributed in the high-order (4-6) streams than the low-order (1-3) streams. The evaluation of ecological stream health, based on multi-metric model of the Index of Biological Integrity (IBI), showed the large difference between the Hw (21.6, fair condition)and Ho (30.5, good condition), indicating that the habitat maintained well chemically and physically had higher distributions of endangered species. Overall, the designation of CER on the Pn should be re-evaluated due to wide-distributions, and the protections from water pollution and the habitat conservations on the endangered species are necessary in the watershed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2B
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• pp.153-160
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• 2006

To recommend ecological flow for major tributaries in Han River basin, the Instream Flow Incremental Methodology (IFIM) have been applied. In particular physical habitat simulation using PHABSIM have been selected for microhabitat variables and QUAL2E model have been used to implement macrohabitat simulation. Habitat Suitability Criteria (HSC) for different life stages in accordance with different hydraulic variables (depth and velocity) have been presented by the field surveying data. We review IFIM procedures and discuss limitations of habitat simulation with specific reference to Han River basin. The results of this research can be used as reference flow for estimation of instream flow in Han River.

• Journal of Korean Society on Water Environment
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• v.28 no.4
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• pp.512-522
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• 2012

This study is focused on fish fauna and distributional features along with physical gradients and stream orders in the Tamjin River basin, Korea. Fish sampling and investigation were conducted for 2 years from 2009 to 2010. Total number of fish species collected were 47 species of 16 family. The group of cyprinidae was mostly abundant. Both fish abundance and biotic index were declined with increasing altitude and longitudinal distance from the river mouth. Two species of Zacco temminckii and Pungtungia herzi were prevalent in most of sampling sites and showed no altitudinal and longitudinal differences. Most other species, however, were spatially restricted to specific regional altitudes. Several species including Zacco platypus, Squalidus gracilis majimae and P. herzi were broadly distributed from river mouth to 50 km. Eight species including Z. temminckii and Rhynchocypris oxycephalus only appeared in over 10 km from the river mouth. Both Odontobutis platycephala and Pseudobagrus koreanus were classified as "upstream dewelling species" observed only in over 30 km from the river mouth. High proportion of tolerant and omnivorous species were more dominated in the downstream zone of the dam, whereas intolerant and insectivorous species were abundant in the upstream zone of the dam. The variable of stream order showed positive relationship between number of fish species and total individuals collected. Sensitive species including insectivore had a declining tendency with increasing stream order, while tolerant specie including omnivore species had relatively increased with stream order. Overall, our study suggested that fish distribution considerably depends on altitudinal gradient and longitudinal distance from the river mouth as well as physical habitat.

• Ocean and Polar Research
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• v.35 no.4
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• pp.441-452
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• 2013

The fish species composition of seagrass bed in Chuuk Lagoon, Micronesia, was investigated every month from August 2009 to July 2011, using a seine net for fish caught. A total of 32 fish species belonging to 18 families under 6 orders were identified during the study period. Of these fish, Atherinomrus lacunosus, and Strongylura incise were the major dominant species representing 85.0% in total number of individuals. The number of species and individuals were high from August to December 2009, 2010. The biomass was highest in September 2010 and the diversity index was higher in September 2009, April, August 2010 and July 2011. The 14 dominant species could be divided into 2 groups of 3 individuals based on appearance patterns; (1) resident species and temporal species (9 species, e.g. Atherinomrus lacunosus), juvenile and adults living in seagrass beds and juveniles living only in seagrass beds; (2) temporal species (2 species, e.g. Hemiramphus lutkei), juveniles living only in seagrass beds; (3) temporal species (3 individuals, e.g. Caranx sexfasiatus). For some species, the appearance patterns were affected by water temperature. However, the relationships between sea currents, salinity, tide, and structure of fish assemblage remain unclear. Further studies that regularly monitor sea grass habitats are necessary to clearly understand the correlation between environmental factors and sea grass habitat use patterns in fish assemblages.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.8
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• pp.2278-2291
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• 2023

Imported ornamental fish should be quarantined because they can have dangerous diseases depending on their habitat. The quarantine requires a lot of time because quarantine officers collect various information on the imported ornamental fish. Inefficient quarantine processes reduce its work efficiency and accuracy. Also, long-time quarantine causes the death of environmentally sensitive ornamental fish and huge financial losses. To improve existing quarantine systems, information on ornamental fish was collected and structured, and a server was established to develop quarantine performance support software equipped with a text search engine. However, the long names of ornamental fish in general can cause many typos and time bottlenecks when we type search words for the target fish information. Therefore, we need a technique that can correct typos. Typical typo character calibration compares input text with all characters in a calibrated candidate text dictionary. However, this approach requires computational power proportional to the number of typos, resulting in slow processing time and low calibration accuracy performance. Therefore, to improve the calibration accuracy of characters, we propose a fusion system of simple Artificial Neural Network (ANN) models and character preprocessing methods that accelerate the process by minimizing the computation of the models. We also propose a typo character generation method used for training the ANN models. Simulation results show that the proposed typo character correction system is about 6 times faster than the conventional method and has 10% higher accuracy.

• Fisheries and Aquatic Sciences
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• v.27 no.4
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• pp.231-239
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• 2024

Geray Reservoir is home to some fish species including Varicorhinus beso, Cyprinus carpio, Carasius carasius, Oreochromis niloticus, and Tilapia randelli. The V. beso is among the top fish-farming species for the reservoir. However, this data on total fish catch showed that the fish population is declining as a result of overexploitation of the stock. The purpose of this study was to set some management measures for the Geray reservoir using some biometric data on the most commonly caught fish-V. beso. A total of 170 fish samples (102 females and 68 males) ranging from 21 to 40.2 cm in total length (TL) and 94.6 to 618.4 g in total weight (TW) were gathered between October 2022 and May 2022 using a cast net with a mesh size of 6 cm. Nonetheless, it is thought that the sampling period is sufficient because the fish were spawning more during the month when the data was collected because of the high concentration of nutrients during that time. The overall male-to-female sex ratio in the population was 1:1.5, which differed considerably from the real ratio of 1:1 (x² = 6.8; p < 0.01). V. beso in the Geray reservoir exhibited virtually an isometric growth (b = 3) considering the length-weight relationships of males (TW = 0.0122TL^2.993) and females (TW = 0.0114TL^3.0139). The V. beso had an absolute fecundity (AF) of 2,190 to 11,265 eggs. AF was significantly correlated with TL, TW, and gonad weight (p < 0.01). V. beso's reproductive season peaked between November and May, with the gonadosomatic index ranging from 0.02 to 20.12 for females and 0.03 to 5.67 for males. The average V. beso condition factors for both sexes were higher than 1, indicating that the fish in the reservoir had properly developed, which may be the result of favorable habitat conditions.

• Korean Journal of Ichthyology
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• v.6 no.1
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• pp.51-59
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• 1994

Morphology of glochidia of two species of Unionidae mussels, Unio douglasiae and Anodonta woodiana were studied based on SEM, and their attachment on Acheilognathus yamatsutae(Acheilognathinae) was observed in the experimentally infected fishes. The glochidia were round-triangle in shape and possessed larval threads, hooks, hooklets, and sensory hairs. Glochidal attachment and cyst formation of the fish were observed without regard to feeding habit and habitat. Density of glochida on the fish (Acheilognathus yamatsutae) was in the order of pectoral fin, dorsal fin, gill and caudal fin. The host fish became encysted about 5-10 hours to the glochidia, and the glochidia detached about 5-6 days after attachment at water temperature $26{\pm}1^{\circ}C$.

• Journal of Korean Society on Water Environment
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• v.28 no.2
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• pp.213-218
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• 2012

Abnormal dissolved oxygen concentration in aquatic habitat, both depletion and supersaturation, can be stress factor to aquatic animals. In this study the nationwide distribution of oxygen supersaturation was analyzed for three categories of streams (43 urban streams, 15 rural streams, and 14 forest streams) by using monitoring network data of the Korean Ministry of Environment. From the distribution analysis 30% of urban streams showed hyperoxic condition of eutrophic level, while no forest stream showed hyperoxic condition. The physiological effect of hyperoxia on fish was examined using two species of fish Zacco koreanus, which resulted in higher concentration of a stress hormone (cortisol) in fish exposed to hyperoxic concentration (196%) of oxygen. This study shows that hyperoxic condition is ubiquitous in urban and rural Korean streams, and it can be a stress factor to aquatic animals.