• Korean Journal of Ichthyology
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• v.29 no.4
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• pp.261-266
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• 2017

Microphysogobio koreensis is an endemic Korean freshwater fish that is protected as an endangered fish by the Ministry of Environment in Korea. In this study, we attempted to investigate the spawning period and spawning characteristics of M. koreensis to obtain basic information for its conservation. Though natural and histological observation, the spawning season occurred between April and May, with peak spawning occurred in early May when the water temperature was $20{\sim}23^{\circ}C$. During the spawning season, males had a bright-orange body and a thick red horizontal line from the rear of the operculum to the caudal peduncle, along with a lateral line, while females had a dark brown body. Nuptial organ had not appeared. The number of eggs in the ovaries was 10,705~22,165 ($15,573{\pm}4,274$). The number and appearance ratio of mature eggs were 1,100~5,920 ($3,383{\pm}2,126$) and 10.3~44.8% ($22.4{\pm}15.6$), respectively. And the size of mature eggs was 0.60~1.00 mm ($0.74{\pm}0.06$).

• Korean Journal of Ecology and Environment
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• v.53 no.2
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• pp.148-155
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• 2020

In this study, we analyzed the effects of the presence or absence of weirs on fish assemblages in wadeable streams (Stream order 1^st~4^th). More specifically, we investigated these effects by evaluating the differences in stream size. The results showed differences in the fish assemblages in third or higher order streams (PERMANOVA, P<0.005). The presence or absence of weirs mainly affected variables such as the number of species the individuals, and species richness index, whereas no difference was observed in the populations of exotic, endemic, and endangered species. A SIMPER analysis showed that the common species Zacco platypus, Zacco koreanus, and Pungtungia herzi are dominant in their corresponding streams (contribution>5%), and that these are the main contributors to differences among the fish assemblages. All these species showed high relative abundances at the sites with weirs. Altered environments by the presence of weirs provided these species with concentrated habitats. In summary, this study analyzed the effects of weirs on fish assemblages on a broad, nationwide, scale, and these results can effectively aid future studies on the specific effects of weirs.

• Korean Journal of Ecology and Environment
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• v.55 no.1
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• pp.49-59
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• 2022

Total of 325 estuaries in Korea were surveyed to analyze the effect of presence of sluice gate on the estuary environment and fish community from 2016 to 2018. Fish community in closed and open estuaries showed differences generally, and the relative abundance (RA) of primary freshwater species in the closed and migratory species in the open estuaries were high. The result of classifying species by habitat characteristics in closed and open estuaries showed similar tendencies at the estuaries of south sea and west sea. The relative abundances of primary freshwater species in the closed estuaries at the estuaries of south sea and west sea were the highest, but estuarine and migratory species were high in both closed and open estuaries at the estuaries of east sea. Primary freshwater species showed higher abundances in the closed estuaries with reduced salinity due to blocking of seawater since they are not resistant to salt. However, primary freshwater species in open estuaries at east sea was higher than that of the closed estuaries, which is considered to be the result of reflecting the characteristics (tide, sand bar, etc.) of the east sea. Korea Estuary Fish Assessment Index (KEFAI) was showed to be higher at open estuaries than closed in all sea areas (T-test, P<0.001), the highest KEFAI was observed in closed estuaries at south sea, and open estuaries in east sea. Fish community of closed and open estuaries in each sea areas showed statistically significant differences (PERMANOVA, East, Pseudo-F=3.0198, P=0.002; South, Pseudo-F=22.00, P=0.001; West, Pseudo-F=14.067, P=0.001). Fish assemblage similarity by sea areas showed a significant differences on fish community in closed and open estuaries at east sea, south sea, and west sea (SIMPER, Group dissimilarity, 85.85%, 88.36%, and 88.05%). This study provided information on the characteristics and distribution of fish community according to the types of estuaries. The results of this study can be used as a reference for establishing appropriate management plans according to the sea areas and type in the management and restoration of estuaries for future.

• Korean Journal of Ichthyology
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• v.24 no.3
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• pp.160-166
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• 2012

Egg development and early life history of the endangered Korean freshwater fish, Microphysogobio koreensis, was investigated to get a basic information for establishing its conservation strategy. The matured adult fishes were sampled at Imsil-gun, Jeollabuk-do, Korea in May 1 2012 and artificially fertilized. The fertilized eggs were spherical, separated demersal and $1.8{\pm}0.14mm$ in diameter. The hatching of the embryo began at about 29 hours after fertilization under water temperature of $23^{\circ}C$. The newly hatched pre-larvae were average $2.2{\pm}0.48mm$ in total length. At 4 days after hatching, the post-larvae were $3.6{\pm}0.55mm$ in total length and york sac was completely absorbed. At 20 days after hatching, their fin rays were formed and finally the larvae entered juvenile stage and grew up to $6.5{\pm}0.77mm$ in total length. At 60 days after hatching, the total length reached $24.4{\pm}1.71mm$, and the band patterns of he head and lateral side were similar to adult fish. Based on this study, the fertilized eggs of M. koreensis hatched more quickly and the pre-larvae length was also smaller, compared with related species.

• Korean Journal of Environmental Biology
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• v.27 no.4
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• pp.369-374
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• 2009

The stumpy bullhead (Pseudobagrus brevicorpus) endemic to Korea is one of critically endangered freshwater fish species. To provide baseline data for its captive breeding and reintroduction we investigated basal characteristics on its growth and sexual maturation in an artificial rearing environment. After 698-day rearing the stumpy bullhead grew up to $89.22{\pm}10.29\;mm$ in total length (TL) and $70.93{\pm}7.68\;g$ in total body weight (BW)($BW=5\times10^{-5}\;TL^{2.678}$; $R^2=0.995$), and showed survival rate of 74.2%. The sex ratio was 1 (471 females) : 1 (473 males), and males ($TL=87.44{\pm}1.07mm$; $BW=8.43{\pm}0.31\;g$) showed significantly faster growth than females ($TL=78.38{\pm}0.92mm$; $BW=6.38{\pm}0.20\;g$) after 663-day rearing. However, condition factor of females was significantly higher than that of males (P<0.05). The number of eggs per female ranged from 508 to 867 (average 734), and their diameters ranged from 0.04 to 1.65 mm. The females which reared about two years in the laboratory condition was able to spawn in the early June after 1~2 days of human chorionic gonadotropin (HCG) injection. The number of hatched fries ranged from 113 to 338 (average 216).

• Korean Journal of Ichthyology
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• v.30 no.2
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• pp.119-124
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• 2018

Diversity of fish fauna and species list collected from the Imha-Dam Reservoir of the Nakdonggang River system were reviewed based on the published materials from 1992 to 2016. As a result of the present study, 46 freshwater fish species/subspecies belonging to 36 genera, 11 families, 4 orders were reported in the Imha-Dam Reservoir. Of them, Cyprinidae occupied 58.7% (27 species), Cobitidae 10.9% (5 spp.), Gobiidae 6.5% (3 spp.), and Siluridae, Centropomidae, Centrarchidae were 4.3% (2 spp.) in the number of species, respectively. The dominant species in the number of individuals was Erythroculter erythropterus (40.1%, 9,333 inds.), and the subdominant species was Opsariichthys uncirostris amurensis (9.8%, 2,281 inds.). Among 46 species/subspecies, 17 species (37.0%) were identified as endemic species to Korea. Three species were endangered fish species by the Ministry of Environment of Korea, five translocated species, and three exotic species were reported.

• Korean Journal of Environmental Biology
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• v.33 no.3
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• pp.314-329
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• 2015

The fish fauna was investigated from 2010 and 2013 at main stream and tributaries in the Seomjin River which has no estuary dike. The collected fishes were identified into 37,751 individuals of 107 species of 81 genera belonging to 41 families. Among the collected fishes the primary freshwater fishes were 57 species (Relative Abundance: 53.3%), the secondary fishes were 10 species (RA: 9.3%) and the marine fishes were 40 species (RA: 37.4%). The dominant species was Zacco platypus (RA: 28.7%), and the subdominant species was Zacco koreanus (RA: 15.0%). The endemic species were 21 species (RA: 31.3%). The endangered fishes were Acheilognathus somjinensis (Level I), Lampetra reissneri (Level II) and Microphysogobio koreensis (Level II). The exotic species were Carassius cuvieri, Lepomis macrochirus and Micropterus salmoides. We supposed that Odontobutis interrupta in the Seomjin River is translocated species.

• Korean Journal of Ichthyology
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• v.10 no.1
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• pp.87-97
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• 1998

The freshwater fish fauna and distribution were investigated in Kojedo from 1982 to 1997. The collected fishes were classified into twenty four species of ten families. Dominant species was Zacco temmincki (relative abundance: 18.1%) and subdominant species was Rhinogobius brunneus (16.4%). Also Iksookimia longicorpus (12.3%), Oryzias latipes (7.5%), Chaenogobius urotaenia (7.5%) and Carassius auratus (6.9%) were numerous. The endemic species of Korea were six species (25.0%) and endangered species were C. splendidus, S. microdorsalis and C. kawamebari. In this study, species diversity index was high at Yoncho stream, dominance index at Aju and Oaepo stream and evenness index at Oaepo stream in community structure. There was a tendency of fish distribution in Kojedo that more longer the stream and more larger the water volume were, there were more species and more individual numbers. It was considered that the dominance of upper and middle reach dwelling fishes resulted in the dominance of Aa type stream mainly. Liobagrus mediadiposalis and L. mediadiposalis ssp. 1 showed different distribution pattern in Kojedo : that is, the former inhabited in east-northern part but the latter in south-western part separately. And the importance of this distribution pattern was discussed in relation to paleogeography.

• Korean Journal of Ecology and Environment
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• v.55 no.1
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• pp.35-48
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• 2022

Fish assemblage of total 325 of Korean peninsula estuaries were surveyed to analyze the characteristics of community structure and diversity by sea areas for three years from 2016 to 2018. The scale (stream width) of Korean estuaries were various (14~3,356 m), and 68.9% of all estuaries showed salinity of less than 2 psu. Total 149 species classified into 52 families of fish were identified, and the dominant and sub-dominant species were Tribolodon hakonensis (relative abundance, RA, 12.5%) and Mugil cephalus (RA, 9.5%), respectively. The estuary of the Korean Peninsula had different physical and chemical habitat environments depending on the sea area, and accordingly, fish community structure also showed statistically significant differences (PERMANOVA, Pseudo-F=26.69, P=0.001). In addition, the NMDS (nonmetric multidimensional scaling) results showed the patterns that indicating fish community difference by sea areas, even though low community similarity within sea area (SIMPER, 21.79~26.39%). The estuaries of east sea areas were distinguished from the others in the aspects of which, the higher importance of migratory fishes and endangered species, and that of brackish species were characterized at south sea estuaries. However, the estuaries of west sea showed higher importance of species that have a relation with freshwater (primary freshwater species, exotic species), which is the result that associating with the lower salinity of west sea estuaries because of the high ratio of closed estuaries(78.2%). The SIMPER analysis, scoring the contribution rates of species to community similarity, also showed results corresponding to the tendency of different fish community structures according to each sea area. So far, In Korea, most studies on fish communities in estuaries have been conducted in a single estuary unit, which made it difficult to understand the characteristics of estuaries at the national level, which are prerequisite for policy establishment. In present study, we are providing fish community structure characteristics of Korean estuaries in a national scale, including diversity index, habitat salinity ranges of major species, distribution of migratory species. We are expecting that our results could be utilized as baseline information for establishing management policies or further study of Korean estuaries.

• Korean Journal of Ichthyology
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• v.26 no.1
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• pp.50-69
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• 2014

Freshwater fish fauna and community structure were investigated at thirty seven stations in the Yeong river, Nakdong river system, Korea from March to October 2013. During the surveyed period thirty nine species and two types belonging to thirteen families were collected. In this collection fishes of Cyprinidae were most numerous possessing 61.0% of all. There were seventeen Korean endemic species including Acheilognathus koreensis, two endangered species such as Koreocobitis naktongensis and Microphysogobio koreensis and two exotic species such as Oncorhynchus mykiss and Micropterus salmoides. Fish species transferred from other native rivers were three species such as Opsariichthys uncirostris amurensis, Pseudobagrus koreanus and Hypomesus nipponensis. Dominant species based on the number of individuals was Zacco koreanus NS (23.24%) and sub-dominant species were Z. koreanus NE (12.72%) and Z. platypus R (12.35%). The community analysis revealed that the structure of fish community in the Yeong river was very stable and diverse in having diversity 1.134, evenness 0.703, dominance 0.110 and species richness 4.348. Fish community was divided into four groups based on similarity indices among surveyed stations such as upper reach, mid-upper reach, middle reach and lower reach group.