• Journal of Life Science
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• v.34 no.2
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• pp.122-127
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• 2024

This study investigated the reproductive ecology and spawning of Hoplobrotula armata on the coast of Jejudo Island. Samples were collected from February to December 2019 and February to December 2020, with a total of 2,634 samples. The results of the investigation showed that total length (TL) ranged from 22.0 cm to 68.8 cm, and the body weight (BW) ranged from 66.5 g to 3,553.9 g. According to the development process of gonads and the gonadosomatic index (GSI), the spawning period of H. armata was from July to October. The relationship between TL and BW was BW = 0.0024TL^3.3278 in females and BW = 0.0035TL^3.2162 in males. The sex ratios of surveyed female to male H. armata was 1:0.71, with more females. At 50%, 75%, and 97.5%, the group maturities of H. armata were as follows: Females, 39.9 cm, 42.7 cm, and 49.4 cm; males, 37.6 cm, 40.4 cm, and 46.9 cm, respectively. According to monthly GSI and gametocyte (ovarian, testis) development stage observations of H. armata on the coast of Jejudo Island, they spawn once a year and are presumed to be summer spawners.

• Korean Journal of Environment and Ecology
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• v.26 no.3
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• pp.367-373
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• 2012

Population ecology (Ecological characteristics) of Squalidus japonicus coreanus from the Namhan River(Yangpyeong-gun Yangpyeong-eup Changde-ri), Gyeonggi-do, Korea were investigated from January to December 2011. Short barbel gudgeon inhabits habitats run of the lower river. The stream bed was mostly covered sand. Their current velocities were 0.14~1.38m/sec and depths were 80~120cm. The sex ratio of female to male was 1 : 0.82. It is presumed that the spawning season is from June to July and water temperatures were $18.5{\sim}24.3^{\circ}C$. Sexually matured individuals appeared over the two year of age. Frequency analysis of total length indicated that the group with 34~50mm in total length was one year old, the 51~74mm was two years old, and the group over 75mm was three years old. The average number of eggs in the ovaries was estimated as 1,871 per matured female. Stomach content of S. japonicus coreanus were Cyanophyta, Chlorophyta, Bacillariophyta, Rotatoria, Crustaceae, Copepoda, Ephemeroptera, Diptera, and Nematoda. omnivorous, mainly feeds on benthic invertebrates such as chironomidae larvae.

• Korean Journal of Ichthyology
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• v.34 no.4
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• pp.270-276
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• 2022

In 2020 and 2022, the habitat of brown trout (Salmo trutta) was investigated in the Soyanggang River in Chuncheon, Gangwon province. As a result of the fish survey, A total of 43 individuals brown trout were identified. The total length of brown trout was widely confirmed from 60 cm or more to less than 10 cm. In January 2020, sperm release and spawn were observed in male and female confirmed at the St. 1. Brown trout were identified stably settled in the Soyanggang River and continues to live. In addition, benthic macroinvertebrates that can act as food sources of brown trout and abundantly inhabited. The riverbed structure is evenly composed of fine gravel and gravel, which constitutes the conditions necessary for habitat and spawning. However, the spawning grounds, spawned eggs and hatched fry have not yet been clearly identified, so continuous research is needed.

• Korean Journal of Ichthyology
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• v.22 no.2
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• pp.90-95
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• 2010

Blue devil (Pomacentrus caeruleus, also called Chrysiptera cyanea) is widespread in the Indo-Pacific Ocean and very popular all over the world as an aquarium fish because it is so easy to keep in a marine aquarium. However, tank-breeding techniques are not completely known. In this study, we reared blue devil and investigated its spawning ecology, as a necessary precursor for successful artificial-tank breeding. We investigated the spawning volume according to time with two types of calendars: solar and lunar. Rearing conditions were set at 30 ppt salinity, $27^{\circ}C$ water temperature, in two aquariums with water volumes of 80 and 125 L. We successfully bred P. caeruleus in this artificial-tank system. The aquarium fish formed a spawning harem with one male and more than two females. We harvested about 113,580 eggs in 44 spawning episodes by two spawning harems during the 11-month period from December to October. They showed a peak season of spawning volume and time in May and June. We confirmed the two peak points in spawning volumes and times, which coincided with the first quarter and last (third) quarter of the lunar phases of the moon.

• 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.

• Korean Journal of Ichthyology
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• v.18 no.3
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• pp.193-201
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• 2006

We researched the reproductive ecology of pale chub, Zacco platypus that inhabits Gajeong-cheon and Wonju-cheon that are a tributary to the Han river. The nuptial organ was formed on the head part, the anal fin and the tail part in male, the change of nuptial color was outstanding. By their changing body shape, the anal fin was extended and body depth came to be high during the spawning season in both sexes. Territorial male of defending behavior were head butting, rotated fighting, parallel swimming, biting and expelling. After pale chub located himself from the upper of the female that was approached to the side parallelling with the female, male and female spawned digging sand with their anal fin by vibrating and any parental care of the eggs was not taken. The spawning interval and lasting time were relevant to individuals density of spawning ground.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.33 no.2
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• pp.97-108
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• 1997

Variation of the catches and fishing grounds, and spawning ecology of Lophius litulon caught by large staw net were investigated from following as ; L. litulon caught through the year, and the peak in catches showed on January in winter, and the lowest catches showed on August in summer. The fishing grounds of L. litulon were located in the Yellow Sea and the East China Sea. And the main fishing ground was formed in the adjacent waters of Ilhyang-cho, where catches and CPUE were more than 50 M/T, 5 kg/haul, respectively, and the range of coefficient of variation(C.V) was 0.6~0.7. The spawning season of L. litulon was on March and April, when spawning area was formed in waters between Ilhyang-Cho and Cheju-Do. The fishing grounds distribution of L. litulon was obviously different with seasonal variation. Namely, in winter, the fishing grounds were mainly formed in the western waters of Cheju-Do, and on March and April( in spawning season), the fishing grounds were densely formed in the adjacent waters of Ilhyang-Cho, and after May, the fishing grounds were widely dispersed towards in the Yellow Sea and the East China Sea with temperature upgrade.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.3
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• pp.367-375
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• 2016

Marbled flounder Pseudopleuronectes yokohamae is a commercially important flatfish in the coastal waters of the East Sea off Pohang, Korea. Maturity and spawning dynamics of P. yokohamae were investigated based on samples collected by gill net and long line in the coastal waters off Pohang from January 2013 to December 2014. We analyzed monthly changes in maturity stage, gonadosomatic index (GSI), egg diameter, fecundity, and total length at 50% group maturity. We found that the spawning period was December to February, wherein fecundity ranged from 55,760 eggs at 20.40 cm total length (TL) to 1,559,007 eggs at 46.6 cm TL. The relationship between TL and fecundity (F) was F = 0.0017 TL^3.5604 (R² = 0.6984), and F increased with increasing TL. We estimated the TL at 50% group maturity as 27.4 cm for female and 23.5 cm for male P. yokohamae, respectively. The results from this research will aid in the development of policies on season and minimum catch length for sustainable production of P. yokohamae. We propose that it is necessary to conduct long-term ecological monitoring for this species because biological properties such as spawning ecology and growth performance are being affected by climate change.

• Korean Journal of Ichthyology
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• v.26 no.1
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• pp.34-41
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• 2014

The present study describes the spawning ecology and early morphological development of Hemitripterus villosus. The natural spawning ground consisted of bedrock and pebbles was the intertidal coast at Taean (Chungnam) and its depth was about 5~10 m. Spawning period was mainly from the end of October to December, when the water temperature and salinity were $6.0{\sim}15.8^{\circ}C$ and mean 32.0‰, respectively. There were no difference of the body shape and color between female and male of Hemitripterus villosus, however its reproductive organs showed clear differences. The male had tube shaped genital papilla, which was connected with testis, and the female had seminal recepacle, which was the lower part of oviduct connected with ovary. Genital papilla of male came out of its body at spawning period and then male copulated. After copulation, female stored the sperm in its seminal recepacle and fertilized when it spawned. Fertilized eggs were reached 8 cells stage after fertilization at rearing water temperature $8.2{\sim}14.9^{\circ}C$. At 29 hours after fertilization, it reached morula stage, and at 146 hours after fertilization, its embryo was clearly formated. Hatching was begun from 1,488 hours (62 days) after fertilization with $8.2{\sim}14.9^{\circ}C$ water temperature. The newly hatched larvae were 12.99~15.46mm(mean $14.16{\pm}0.65$ mm) in TL (Total Length), and its mouth and anus were open. At 7 days after hatching, its yolk sac was completely absorbed and the myotomes were 15+25=40, measuring 15.23~15.54mm(mean $15.39{\pm}0.22$ mm, n=5) in TL. At 75~80 days after hatching, it was measured mean $30.06{\pm}0.76$ mm in TL, and it had reached the juvenile stage with the complete set of fin rays.

• Korean Journal of Environment and Ecology
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• v.35 no.3
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• pp.285-293
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• 2021

This study was conducted to elucidate spawning period characteristics and early life development of eight barbel loach, Lefua costata (Balitoridae) at the Jusucheon stream, Okgye-myeon, Gangneung-si, Gangwon-do, Korea between January and December in 2018. The spawning period was estimated to be from May to August, considering the change in the gonad-somatic index, the appearance of young fry, and frequency distribution in egg diameter. It was a multi-spawning type. The gender ratio was 1:0.79 with 1,117 females and 879 males collected. The egg size was 0.24-0.93 mm, with mature and immature eggs found during the spawning period. The size of mature eggs was 0.71±0.02 mm, and the average number of fecundity was 1,786±818 (n=31). Observation of the egg development showed that the fertilized eggs were the sticky, gray, segregated, and demersal type with 0.76±0.03 mm in diameter. The hatching of the embryos began at about 34 hours (hatching rate 50%) after fertilization underwater temperature of 25℃. The average length of the newly hatched pre-larvae was 2.7±0.11 mm. The average length of pre-larvae at 4 days after hatching was 4.5±0.16 mm, and the yolk sac was completely absorbed and entered the post-larvae stage. At 20 days after hatching, the average length of post-larvae was 11.5±0.67 mm, and their fin rays were formed before they transitioned to the juvenile stage. At 100 days after hatching, the average length reached 49.8±2.60 mm, and the appearance and the lateral sideband patterns were similar to those of the adult fish.