• Korean Journal of Ichthyology
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• v.26 no.1
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• pp.1-10
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• 2014

Population ecology of Gobiobotia naktongensis was investigated at the Gamcheon stream, Nakdonggang River in Korea from March to November in 2010 and June in 2012. It mainly inhabited on the slow-flowing waters 0.11~0.44 m/s (mean: 0.32) and shallow depth 11~69 cm (mean: 28). As a result of the sieve analysis, size of the particles in the stream bottom beds consisted of 1.71% (>3.35 mm), 71.3% (>0.500 mm) and 26.9% (>0.106 mm). The standard length of the population indicated that the age for 25~30 mm group is one 31~41 mm group is two and longer than 42 mm group over three (May in 2010). The spawning period was from June to July with water temperatures ranging from 28.0 to $31.0^{\circ}C$. The sex ratio of female to male was 1 : 0.64 while the number of eggs in the ovaries was 1,067~7,298 (mean: 2,827). The number of matured eggs size in ovaries was 0.71~1.04 mm (mean: 0.79) and the stomach contents were mainly Chironomidae. The individual number of stomach contents was increased at noon and showed the highest rate from noon to 3 pm.

• Korean Journal of Environment and Ecology
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• v.27 no.2
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• pp.230-240
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• 2013

The fish fauna and population characteristics of Zacco platypus at the 9 habitat types in the Hongcheon River were investigated from August, 2009 to April, 2010. The collected species during the surveyed period were 21 species belong to 6 families. Korea endemic species were Acheilognathus signifer, Microphysogobio longidorsalis, Pseudopungtungia tenuicorpa, Squalidus gracilis majimae, Zacco koreanus, Iksookimia koreensis, Silurus microdorsalis, Liobagrus andersoni, Coreoperca herzi, Odontobuitis interrupta, and Odontobuitis platycephala which showed 61.9% ratio of total species. Dominant species was Z. koreanus, and subdominant species was Z. platypus. Dominant species according to habitat types were Z. platypus(in side channel, substrate type pool, and riffle), Z. koreanus(channel connected pool, run, meander type pool, and rock type pool), M. yaluensis( dam type pool ) and Rhynchocypris oxycephalus(channel unconnected pool). Length-weight relationship in the population of Z. platypus was 3.27 in regression coefficient(b). Principal component analysis was classified as 2 groups. Bray-curtis cluster analysis indicated that the channel connected pool and meander type pool showed the most similar values(66.2%), whereas side channel and channel unconnected pool exhibited the most distance values(32.1%).

• Korean journal of applied entomology
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• v.28 no.4
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• pp.229-236
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• 1989

A combined field release of indigenous larvivoroug fish (Aplocheilus latipes) and hybrid herbivore (Tilapia mossambicus miloticus) was conducted to determine the effectiveness of biological control, in particular, against malaria vector (anopheles sinensis), breeding in weedy habitat of rice fields at the University rice paddies at Suwon during the period of June through September in 1988. A combined fish introduction at the release rate of 2.0 fish per $M^{2}$ for Aplocheilus and 1-pair $10M^{2}$ water surface for Tilapia resuited in 70.8% Anopheles larval reducton in a week period, the rates of rontrol increased to 73. 5% and 80.2% in 4th and 5th week respectively after the fish introdurtion, maintaining mosquito suppression in range of 80~82% control after the 5th week against Anopheles and Culex spp. combined. In a single fish treatment with Aplocheilus at 2.0 $fish/M^{2}$ release rate, Anopheles larval reduction ranged on the average 51.4~56.5%in 4 wrek period which was later integratpd with B.t.i. (Rl53.78) treatment at 1.0 kg/ha dosage rate to suppress vector mosquito population down and the the results was compared with that of combined fish introdurtion.

• Korean Journal of Ichthyology
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• v.12 no.2
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• pp.101-110
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• 2000

Population ecology of Rhynchocypris keumgangensis have been investigated at upper part of the Han River in Korea from January to December, 1995. The habitat was low water temperature and clean area, and stream form was Aa. The major cohabitation fish was Phoxinus phoxinus. The total lengths in this population indicated that below 40 mm group is one year old, 40~65 mm group is two years old, 65~80 mm group is three year and the 80 mm longer group is regarded over four years old. There were no differences in total length distribution between the female and the male. The males became sexually mature, when longer than 45 mm and females longer than 65 mm in total length. Spawning season was from April to mid May with the water temperature in $11{\sim}14^{\circ}C$ and the properous period was April. The mean number of eggs in ovary was 1,616. The sex ratio all the year round of the female to the male was 1 : 0.75. The current velocity of the spawning ground was 44 (20~80) cm/sec and water depth was 35 (5~70) cm. Eggs were laied in 5~15 cm deep underneath the immaculate pebbles (2~6 cm). Sex ratio of the female to the male was 1 : 6.90 for spawning behavior.

• Korean Journal of Ichthyology
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• v.35 no.4
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• pp.333-339
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• 2023

The aim of this study was to collect information regarding the sex ratio, size at sexual maturity, and the primary spawning period of Hexagrammos otakii. The sex ratio (female : male) was observed to be 1 : 1.2 (n =739 : 906, with females comprising 81.6% of the population). The gonadosomatic index (GSI) exhibited its highest values in November for females and October for males, coinciding with the primary spawning period from November to January. The total length required for 50% sexual maturity was determined through a logistic regression model and found to be 23.1 cm for females.

• Korean Journal of Ecology and Environment
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• v.37 no.2 s.107
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• pp.227-235
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• 2004

Fish fauna and community structure were surveyed in the Nakdong River, Gumi City, Kyeongpook province from April 2001 to July 2002. During the surveyed Period, 39 species, 32 genera belonging to 10 families were collected. Cyprinid fish occupied 64.1% (25 species) and cobitid fish had 7.7% (3 species). Fourteen species(35.9%) of observed species were known as endemic species. The exotic fish was Micropterus salmoides (2.5%) . The dominant species were Zacco platypus (relative abundance: 36.7%) and Opsariichthys uncirorstris amurensis (22.7%). Carassius aurafus and Microphysogobio rapidus were numerous (4.0${\sim}$4.3%). The rare species comprising less than 0.15% were Acheilognathus koreensis, Aphyocypris chinensis, Iksookimia longicorpus, Coreoleuciscus splendidus, Rhinogobius giurinus, Sarcocheilichthys variagatus wakiyae, Silurus asotus astus, and Channa argus. It was found that the population density of carnivorous Opsariichthys uncirostris amurensis increased drastically in the mid-reach of the Nakdong river since it had been introduced from the other native rivers in the middle 1990s. Gobiobotia nakdongensis inhabit riffle (water velocity : 0.43${\sim}$0.67 m $s^{-1}$) of which the river bed is mainly sand. This species is considered to be in need of conservation. As the result of analyzing fish community in the surveyed area, the species diversity, evenness and dominant indices were 1.008, 0.663 and 0.196 respectively. The findings showed that the tributary, which the waterside plants were abundant and had various habitats, had a higher species diversity (1.112) than the main river (0.787). Sand mining had been disturbing the river ecosystem of the study stations 3, 11, 13 & 14, and these stations showed a quite low species diversity (0.421 ${\sim}$0.574).

• Korean Journal of Ecology and Environment
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• v.44 no.2
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• pp.226-238
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• 2011

Ichthyological fauna and community structure were surveyed in the Naeseong Stream around the planed Yeongju Dam, Yeongju City, Gyeongsangbuk-do from April 2007 to October 2009, During the survey period, 27 species (25 genera, 10 families) were collected. Cyprinid fish comprised 63.0% (17 species) and cobitid fish comprised 7.4% (2 species). Ten of the 27 species (37.0%) were endemic species. The dominant and subdominant species based on the number of individuals was Zacco platypus (43.2%) and Zacco koreanus (15.8%), respectively. Introduced from the other native rivers and exotic fish were Opsariichthys uncirostris amurensis, Leiocassis ussuriensis, and Micropterus salmoides (11.1%). The declining population density of Zacco koreanus and its subdominant status represents a change, since, up until the mid 1990's, it was widely distributed throughout the area and was the dominant species. The distribution area of Zacco koreanus decreased in size; by 2009, it no longer inhabited the lower reaches of the Naeseong Stream. On the other hand, Zacco platypus remained the dominant species throughout the area, except for the upper-reaches of the water-course. Gobiobotia naktongensis inhabited all areas of Naeseong Stream, which mainly has a sandy bottom. Analyses of the fish community revealed species diversity, even-ness and dominant indices were 0.881, 0.615, and 0.230 respectively. These results showed that the main river, in which the water width and flow are abundant and which has various habitats, has a higher species diversity (0.829) than the tributary (0.735).

• Korean Journal of Environment and Ecology
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• v.27 no.4
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• pp.437-448
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• 2013

The ichthyofauna and fish community were studied in Daecheon Stream from April to October 2012. During the survey period a total of 42 species belonging to 13 families were collected. Dominant species by number was Zacco platypus(32.3%) and Tridentiger brevispinis(12.8%). In biomass, the dominant species was Z. platypus(27.7%) and Chelon haematocheilus(11.9%). Also, eight Korean endemic fish species and one endangered species (Rhodeus pseudosericeus) were collected. In addition, two exotic species(Carassius cuvieri and Micropterus salmoides) and migration fish species(Anguila japonica) were observed. Based on the length-weight relationship of Z. platypus, the b value was 3.21~3.29, and the condition factor(K) was 0.89 on average with stable condition. According to similarity analysis, fish communities in Daecheon Stream were divided into three groups; the upper reaches near a reservoir(St. 1), the middle reaches (St. 2 to 4) and the lower reaches near a weir(St. 5). Dominant species at each group were Zacco koreanus(St. 1), Z. platypus(St. 2 to 4) and T. brevispinis(St. 5). This result suggested that artificial structures such as dam and a weir have a marked effect on the distribution of fish communities in Daecheon Stream.

• Korean Journal of Ichthyology
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• v.24 no.4
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• pp.272-277
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• 2012

The feeding habits of black scraper, Thamnaconus modestus, were studied using 172 specimens collected in the coastal waters of Geomun-do, Korea. The size of the specimens ranged from 16.2 to 39.1 cm in standard length (SL). T. modestus was a omnivore that consumes mainly benthos. Of the benthos species nephtheidae was the most preferred prey. Its diet also includes, algae, thoracica, gastropoda, desmospongia. Small and medium size individuals (<21~33 cm, SL) fed mainly on nephtheidae and algae. Larger individuals (>33 cm, SL) fed mainly on thoracica. The proportion of nephtheidae decreased as body size increased (>33 cm, SL), whereas the consumption of thoracica gradually increased.