• Korean Journal of Environment and Ecology
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• v.31 no.2
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• pp.166-173
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• 2017

Morphological and population characteristics of the Cottus koreanus were investigated at Hoam stream from October 2015 and April 2016. This is the first record on C. koreanus not only from Hoam stream (the upstream region of Daejong stream, Gyeongsangbuk-do Gyeongju-si Yangbuk-myeon Hoam-ri) but also from the stream flowing into the Samcheogosip stream, in the southern part of East Sea, Korea. The distribution of C. koreanus ranged from Girim temple to Yongyeon waterfall, about 1.2 km, and the water surface were about $3,600m^2$. The population size was assumed to 1,656 individual number, 46 object per $100m^2$. The morphometric characteristics of C. koreanus in the Hoam stream and the Han river are very similar except that the population at Hoam stream shorter head length, ventral fin ray length, pectoral fin ray length and mouth width when compared with the population at Han river. Other than that, the two populations showed the same meristic characters. Frequency analysis of total length indicated that the group with 40~59 mm in total length was one year old, the 60~79 mm was two years old, and the group over 80 mm was three years old. The average number of eggs in the ovaries was estimated as 361 (239~468) per matured female. The number of matured eggs size in ovaries was $2.6{\pm}0.21$ (23.~3.1) mm and this species was large eggs type. Calculation of the length-weight relation of C. koreanus showed the value of constant a as 0.00001 and b as 3.01, and the Condition factor (K) was 1.26 an on average.

• Applied Microscopy
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• v.28 no.4
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• pp.447-463
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• 1998

This study was carried out to investigate the histomorphological changes and the electrophoretic patterns of egg components, obtained from 100 of 2-year-old female catfishes (Silurus asotus). Female Korean catfishes collected in the vicinity of Chollabukdo have synchronous ovaries which discontinously ovulate eggs during the breeding season (from late May until early July). The fishes were killed by severing the spinal cord just posterior to the head after immobilization with tricaine methanesulfonate (MS 222). Especially, the light microscopic and ultrastructural changes of ooplasm and follicular membranes of oocytes, were examined by means of light and transmission electron microscopy. The size of the nucleoli and number of the yolk granules increased as the oocyte groved. Yolk granules were deposited in the oocyte as fluid Due to tile presence of large early and late maturing oocytes, their ovaries were enlarged, transparent, granular and greenish in color. As the percentages of fish in late maturing oocyte (LMO) and ripe oocyte (RO) stage increased from March to April, mean gonadosomatic index (GSI) values (19.95%) increased. Zona radiata changed from squamous into cuboid in shape in the early maturing oocyte (EMO) stage. Processes, microvilli, from the zona radiata and from the oocyte grow, and make contact with each other in the pore canals of the zona radiata during vitellogenesis, but are withdrawn as the zona radials becomes more compact and devoid of pore canals during oocyte maturation. Seasonal changes in the microscopic appearance of the ovaries were well correlated with those in both gonadosomatic index and macroscopic appearance. The main cytological changes such as increase in size of cell, nucleus, nucleolus, and increase in number of nucleoli and mitochondria demonstrated with electron microscopy in the previtellogenic oocytes of Korean catfish, provided evidences for important synthetic processes in an early preparatory phase of oocyte development. The electrophoretic pattern of major band in mature stage was much thicker (24 k, 66 k, 90-110k dalton) than that in previtellogenic phase.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.3 no.1
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• pp.19-26
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• 1970

During the summer of 1969, a series of experiments on the spawning and development of the eggs of grass carp and silver carp was performed with the following results, but the complete development of eggs Iras not accomplished: 1. The season of maturity for both species is estimated to be from the end of June to the beginning of August. 2. Pituitary glands for the use of inducing maturation should be obtained before the maturation season of its donor. 3. Silver carp as small as 40 cm in body length (48 cm in total length) with an age of 6 years were found to have reached maturity, and the number of eggs in the ovaries were from about 23 to 26 thousand for those with body lengths of 40-44.5 cm. 4. The conical-shaped net cloth incubator worked better than others, and each incubator was most effective when installed in parallel series to the water supply pipe with a valve for each incubator to control water flow. 5. During the egg development, if any cell or cells were displaced, the eggs eventually died. 6. The proper manipulation of brood fish before the egg-taking seems to be very Important, and close care should be paid to feeding them well and keeping them in a pond of proper water depth.

• 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.30 no.5
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• pp.888-895
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• 2016

The population ecology (Ecological characteristics) of Squalidus chankaensis tsuchigae were investigated at Geum River from March to November, 2013. This species inhabited midstream of the river where was mostly covered with cobble and sand. The depth of the habitat was 30~60 cm and velocity of stream was 2.27~4.88 cm/sec. The sex ratio of female to male was 1 : 0.86. They were sexually mature when they were over two years of age. The spawning period was from June to July with water temperatures from $25^{\circ}C$ to $25^{\circ}C$. Sexually matured individuals appeared over the two year of age. Frequency analysis of total length indicated that the group with 55~70 mm in total length was one year old, the 71~90 mm was two years old, and the group over 91 mm was three years old. The average number of eggs in the ovaries was estimated as 2,219 per matured female. The number of matured eggs size in ovaries was 0.64~0.98 (mean: 0.85) mm. Calulation length-weight relation of S. chankaensis tsuchigae show the value of contant a as 0.0002 and b as 2.81, and condition factor (K) was 1.06 on average. The stomach contents were Cyanophyta, Chlorophyta, Bacillariophyta, Crustaceae, Copepoda, Nematota, Actithocephala, and Ephemeroptera, Hemiptera, Diptera, and Trichoptera that belong to Aquatic insect, and dormant bud of Pectinatella that belongs to Phylactolaemata. The diet of S. chankaensis tsuchigae was omnivorous, mainly vegetable feed on attached algae (filament form), and mainly animality feeded on benthic invertebrates such as Chironomidae larvae.

• Korean journal of applied entomology
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• v.49 no.2
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• pp.115-121
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• 2010

The bean bug, Riptortus clavatus Thunberg (Hemiptera: Alydidae), is a pest of soybeans and tree fruits. It enters reproductive diapause during winter. We studied the effect of different combinations of temperature, day length, and treatment period on the termination of diapause in R. clavatus using adult females collected in October and November 2006. Ovarian development was used to determine diapause termination. The treatments were: (1) HTLD; $25^{\circ}C$, 14L:10D treatment for 1, 2, 3 weeks and 30 days, (2) HTSD; $25^{\circ}C$, 10L:14D treatment for 1, 2, and 3 weeks, (3) LTLD; $8^{\circ}C$, 14L:10D treatment for 1, 2, and 3 weeks followed by HTLD for 3 weeks, and (4) LTSD; $8^{\circ}C$, 10L:14D treatment for 1, 2, and 3 weeks followed by HTLD for 3 weeks. The HTSD treatments did not affect ovarian development, and resulted in no significant difference in the number of mature eggs in ovaries or the percentage of diapause-terminated females compared to the control females before treatment. The percentage of females that terminated diapause was significantly higher in the HTLD treatment than in the HTSD treatment. The HTLD treatment for more than 14 days increased the percentage of diapause-terminated females, accelerated the development of the ovaries, and increased the number of mature eggs in ovaries. Compared with the HTLD or HTSD treatments, the LTLD or LTSD treatments followed by the HTLD treatment accelerated ovarian development and increased the number of ovipositing females. The pre-LTSD treatment for 1 week was enough to increase the number of eggs oviposited.

• Korean Journal of Ichthyology
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• v.27 no.2
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• pp.78-85
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• 2015

Population ecology of Rhodeus uyekii (Pisces: Acheilognathinae) was investigated at the Bongseocheon, Mankyeonggang (River) in Korea, from January to December 2014. It mainly inhabits the slow-flowing waters having mud bottoms. Measurement of the standard length of the population indicated that the following standardization: 24~29 mm are one year old, 30~35 mm are two years old, 36~39 mm are three years old, and >40 mm group are regarded over four years old (October in 2014). The spawning season was from March to June, with water temperatures in the range $11.5{\sim}27.0^{\circ}C$. The sex ratio of female : male was 1 : 0.77. The number of eggs in the ovaries was 104~168 ($mean{\pm}SD$: $124{\pm}18.1$). The size of the matured eggs was 2.8~3.5 ($3.2{\pm}0.15$) mm in the long axis, and 1.4~1.5 ($1.4{\pm}0.03$) mm in the short axis. The eggs were found in Unio douglasiae and the number of eggs, larvae or both was 3~18 ($10.2{\pm}5.0$). Stomach contents were mainly phytoplanktons such as the genera Navicular, Cocconeis, Cymbella (Bacilariophyceae) and Cloniophora (Chlorophyceae).

• Korean journal of applied entomology
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• v.60 no.2
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• pp.175-183
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• 2021

As a baseline study of (common name) Locusta migratoria (Orthoptera: Acrididae) to utilize as a food source, we investigated the developmental characteristics of ovaries and eggs. Locusta migratoria had a pair of ovaries and more than 90-104 panoistic ovarioles. The ovary length in the adult stage was longer than it is in the 5th nymph stage. The length on the first day of the adult stage was 2.5-fold longer than the first day of 5^th instar. The ovary length showed a tendency to increase until the 30th day of the adult phase, but decreased from the 35^th day. Ovarioles length was about half of the ovary length, showing a similar tendency to the variation of ovary length. The lengths of the ovaries and the ovarioles increased proportionally to body weight. The matured eggs were identifiable from the 15^th day of the adult stage, and the number was the highest on the 30^th day at 50.6 individuals. Spermatheca size was also affected by the ovary development. The ovaries of L. migratoria were highly matured until the 30th day of adult stage. Weight and size of eggs increased sharply from the 4th day after egg oviposition and remained from the 7th day after spawning. Based on the above results, we found that the ovary of L. migratoria was most developed on the 30th day of adult phase, and 1st nymph is being hatched on the 10th day of the oviposition.

• Korean Journal of Environment and Ecology
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• v.33 no.6
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• pp.677-685
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• 2019

We investigated the ecological characteristics of kumgang fat minnow (Rhynchocypris kumgangensis) in the Eocheon stream from October 2017 to September 2018. The water temperature was 10.2- 14.3℃ and remained below 15℃ during the year. The fishes in cohabitation with kumgang fat minnow were Cottus koreanus (16.62%), Phoxinus phoxinus (10.74%), Rhynchocypris oxycephalus (1.55%), Oncorhynchus mykiss (0.56%), Zacco koreanus (0.28%), and Iksookimia koreensis (0.14%%). The ratio of females to males was 1:0.91 and did not vary widely. The frequency analysis of total length indicated that the fishes with less than 40 mm in total length were one year old, those with 40 - 69 mm were two years old, those with 70 - 84 mm were three years old, and those with 85 mm or more were four years old for individuals collected in May through June. The sexually mature fishes were over two years old. The spawning season was from late May to late August, and the water temperature was 12.5~14.5℃ during the period. The prosperous spawning season was from June to July, and the water temperature was 13.6 - 14.5℃ during the spawning period. The average number of eggs in the ovaries was 1,006 (664 - 1,666) per matured female, and the matured eggs were yellowish and spherical with a mean diameter of 1.34±0.17 mm. The length-weight correlation of R. kumgangensis was BW = 0.00003TL^2.77 with the constant a as 0.00003, b as 2.77, the average condition factor (K) as 1.04(0.65~1.48), and the slope as -0.0012. The kumgang fat minnows inhabiting in the spring water had a longer spawning period, a fewer number of eggs in ovaries, and the lower condition factor (K) than those inhabiting other areas.

• Korean Journal of Ichthyology
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• v.17 no.2
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• pp.112-122
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• 2005

Iksookimia longicorpa was investigated in the upper part of the Seomjin River in Korea from 2003 to 2004. It inhabited pebble and cobble bottoms with water-current velocities of 10~30 cm/sec and depths of 30~100 cm. This species is active during daylight hours from March to October but hibernated in the river bottoms in the winter season. The sex ratio of female to male was 1 : 0.65, and the female was 20~40 mm larger than the male. Female length frequencies in this population indicated that the 65~90 mm group is 1+years old, the 90~110 mm group is 2+ years old, and the 110~130 mm group is 3+ years old. The males developed a secondary sexual character, the lamina circularis at the base of their pectoral fin, after 13~14 months. The spawning season was from early to middle June with water temperatures of $20{\sim}24^{\circ}C$ individuals became sexually mature after the age of 2 years. The average number of eggs in the ovaries was $2,402{\pm}944$. Stomach contents were mainly Chironomidae, Ephemeroptera, Arcellidae and Algae. The feeding rate was highest in April and September; they did not fed in the winter.