• Korean Journal of Ichthyology
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• v.20 no.2
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• pp.97-104
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• 2008

Comparative study of retinal structure in two Korean endemic freshwater fishes, Zacco koreanus and Pseudobagrus koreanus, was carried out by light and scanning electron microscopy. In the visual cell layer comprised of cone cells and rod cells, the cone cells showed a distinct difference between both species. Z. koreanus had two types of cone cells, single cone cells including a long single and short single cone cells, and double cone cells, whereas P. koreanus had only one type of single cone cells having no its short single and long single cones. Meanwhile, the cone cells of Z. koreanus were arranged in more compact-rowed pattern, but it was more loose and irregular in P. koreanus. Based on field observation, Z. koreanus is mainly a epipelagic or sometimes benthopelagic and a diurnal fish with a round and large eye, while P. koreanus is a demersal and nocturnal fish with an oval and small eye. Therefore, the difference in the retinal structure of two species seems to be closely related to their ecological habitats.

• Korean Journal of Environmental Biology
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• v.25 no.4
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• pp.378-384
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• 2007

Some of ecological factors and the early life history of endangered freshwater fish, Pseusobagrus brevicorpus, were investigated to proliferate artificially and to restore the population by release seedlings. The density of population in restricted area by small scale dam was 1.25 ind. $m^{-2}$, and the low capacity for reproduction having 200$\sim$250 eggs ind$^{-1}$. were thought to be a reason of this endangered situation. From the result of induction of natural spawning in aquarium after hormone injection it was considered that the spawning substrate would be aquatic plants with slender branches. The hatching was observed after 50 hrs after fertilization and the larvae showed aggressive behavior. Yolk was almost absorbed 3 days after hatching, and the larvae shaped tad-pole grew up to fry after 30 days. We discussed on the strategies for conservation of this species according to those results from investigation on ecology and early life history.

• Korean Journal of Environmental Biology
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• v.39 no.2
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• pp.207-217
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• 2021

Using the data from the national survey of fish, we determined the population size and the distribution of Micropterus salmoides, which is a translocated species into the aquatic ecosystem of Korea. . The spatial concentration of this species was determined by performing an optimized hot spot analysis. After determining potential invasiveness and risk assessment, we measured the disturbance of biodiversity in the aquatic ecosystem. The result of distribution analysis indicates that the population of M. salmoides was concentrated in the major basins of Han river, Geum river, Nakdong river, and Yeongsan-Seomjin river, including the Jeju island. In particular, Nakdong river basin showed the highest appearance rate. On the contrary, Yeongsan-Seomjin river basin showed the lowest appearance rate. The Nakdong river and the Nakdong river basin were the areas with the high spatial concentration of M. salmoides. On the other hand, only Han river basin and Geum river basin had the lowest spatial concentration. The fish invasiveness screening kit(FISK) was used to assess M. salmoides, which inhabited a broad region of aquatic ecosystem: the assessment score was 31.0, indicating its 'highly invasive' nature. Our study aims to encourage research that improves the biodiversity and the conservation of M. salmoides in a priority area.

• Journal of Environmental Impact Assessment
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• v.20 no.6
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• pp.845-856
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• 2011

In order to establish fundamental data for stream restoration and environmental flow, we investigated inhabitation and species diversity of fish to substrate size in the typical streams of Geum River Basin. Field monitoring including fish sampling was conducted from October 2007 to October 2009. Substrate size was determined according to six different : silt (Si), sand (Sa), fine gravel (Fg), coarse gravel (Cg), cobbles (Co) and boulders (Bo). A total number of fish caught in the 18 sites was 7,649 representing 10 families 50 species, and Si, Sa, Fg, Cg, Co and Bo stations occupied 30, 29, 38, 30, 27 and 17 species, respectively. The most frequently found species in number was pale chum (Zacco platypus, 29.7%, n=2,275) followed by Z. koreanus (22.5%, n=1,720) in total stations. Biological diversity with increase of substrate size from the dominance of part species showed higher values as dominance index, lower and diversity, richness and evenness index. Index of biological integrity (IBI) and qualitative habitat evaluation index (QHEI) scores decreased with increase of substrate size. Therefore, it is necessary to make an effort on stream rehabilitation with evaluation of physical habitat condition by indicator species in order to maintain biodiversity and perform ecological restoration.

• Korean Journal of Environmental Biology
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• v.41 no.4
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• pp.637-656
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• 2023

River estuaries are dynamic and productive ecosystems with high regional biodiversity. Environmental DNA (eDNA) has become a useful approach to assessing biodiversity in aquatic ecosystems. This study was conducted to investigate fish community characteristics and species diversity in two river estuary ecosystems, the Taehwa River and Changwon Stream. We further compared conventional and eDNA metabarcoding analyses of the fish communities. The conventional survey was performed in May, July, and October 2022, while the eDNA analysis was conducted only in May. We observed various fish species with different life histories, including carp, goby, and marine fish. We also found that migratory fish, such as dace Tribolodon hakonensis, sweetfish Plecoglossus altivelis, and eel Auguilla japonica, occurred in the Taehwa River, suggesting high river connectivity. Marine fish species were predominant in the Changwon Stream, as this river is located close to the sea. The diversity indices showed that the Taehwa River generally had higher species richness, evenness, and diversity values than the Changwon Stream. A total of 9-19 species were detected in the conventional survey for the three sites, whereas 11-18 species were found from eDNA analysis. The findings indicate that the sensitivity of eDNA was similar to or higher than that of the conventional method. Our study findings suggest the efficiency and efficacy of eDNA-based fish community monitoring, although with some shortcomings in applying the genetic marker to Korean fish, including no clear-cut distinction for Korean endemic species and/or genetically closely related species groups.

• Korean Journal of Ichthyology
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• v.24 no.3
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• pp.234-241
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• 2012

Kichulchoia brevifasciata belonging to family Cobitidae is an endemic Korean freshwater fish and restricted to very small areas such as Goheung peninsula, and Geogum Island and Geumo Island flowing into the South Sea. As a decrease of its population was further accelerated, a close investigation on the distribution was required. Among a total of 21 sites surveyed, only 5 sites were confirmed in which K. brevifasciata existed. Based on this result, we classified the 5 sites into 3 categories: Being worthy of preserved, being subject to threaten and staying in good condition.

• Korean Journal of Ichthyology
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• v.28 no.3
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• pp.175-178
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• 2016

The karyotype analysis of Liobagrus somjinensis, an endemic Korean freshwater fish with restricted waters and a new species of torrent catfish was carried out from nine females and eight males of Somjingang River, Sikjeong-dong, Namwon-si, Jeollabuk-do, Korea. The diploid number of chromosomes was 42, and its karyotype was composed of 28 metacentrics and 14 submetacentrics; 84 FN (fundamental number). Polyploidy and sex dimorphism were not observed in the present species. The chromosome number of L. somjinensis was the same as its congeners, but there was a difference in karyotypes.

• Fisheries and Aquatic Sciences
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• v.18 no.4
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• pp.405-410
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• 2015

The Korean lumpsucker, "Do-chi", reported previously as Eumicrotremus orbis, was reinvestigated on the basis of specimens collected from Korea, Japan, and the USA. Morphological and genetic analyses showed that "Do-chi" corresponds to Eumicrotremus taranetzi and clearly differs from E. orbis. Eumicrotremus taranetzi is readily distinguishable from E. orbis by its large, high spiny tubercles with weak, small or no prickles (small, low spiny tubercles with distinct prickles in E. orbis) and 3-4 pairs of spiny tubercles in the dorsal rows (five pairs in E. orbis). We compared partial sequences (466 bp) of the mitochondrial cytochrome c oxidase subunit I genes of "Do-chi" and other Eumicrotremus species. "Do-chi" and E. taranetzi were clustered by the smallest Kimura two-parameter genetic distance (d = 0.000-0.002) and were clearly separated from E. orbis (d = 0.035-0.037). Therefore, our results suggest that the scientific name of the Korean lumpsucker, "Do-chi" should be changed to E. taranetzi.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.3
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• pp.298-304
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• 2018

A single specimen of Gymnothorax pseudothyrsoideus (424.0 mm TL) belonging to the family Muraenidae, order Anguilliformes, was collected from Jeju Island, Korea, for the first time. The specimen is characterized by jaws closing completely, canine teeth on jaws, teeth not exposed when mouth is closed, ovoid posterior nostril, and body color ranging from yellowish brown to brownish with small dark spots aggregating to form larger spots that from approximately four irregular rows along the body. A comparison of mitochondrial DNA 16S rRNA sequences indicated that this specimen corresponds well with G. pseudothyrsoideus (K2P distance, d=0.002) but differs from other Gymnothorax species (11.9-13.7%). Therefore, the new Korean name "Geu-mul-nun-gom-chi" is proposed for the species G. pseudothyrsoideus.

• Korean Journal of Ichthyology
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• v.18 no.3
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• pp.273-279
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• 2006

A taxonomic study of the family Zoarcidae was conducted using fish collections deposited in the Department of Biology, Chonbuk National University, Jeonju, Korea and the East Sea Fisheries Research Institute, Korea. Among these collections, the following four species of the genus Lycodes are recognized as the first records for Korea; L. sadoensis, L. japonicus, L. pectoralis, and L. sigmatoides. These species are here redescribed and figured, with their distributions and a provisional key to five genera and eleven species of the family Zoarcidae from Korea.