• The Korean Journal of Malacology
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• v.17 no.2
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• pp.79-84
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• 2001

In order to obtain the basic information for seedling production of the scallop, Patinopecten yessoensis, the egg development and larva growth were investigated at different conditions such as water temperature, salinity and phytoplankton. Eggs were demersal isolated eggs, which averaged 77.3${\pm}$2.7$\mu\textrm{m}$ in diameter after spawning. The fertilized eggs developed to D-shaped larva of shell length 117.5${\pm}$3.8$\mu\textrm{m}$ after 60 hours at 15$^{\circ}C$. The range of water temperature and salinity during egg development were 10-20$^{\circ}C$ and 28-34 ppt, respectively. The time of egg development was shorter with higher water temperature. After 10 days of spawning, D-shaped larva reached 160 $\mu\textrm{m}$ in shell length, and after 25 days became full-grown larva 250 $\mu\textrm{m}$ in shell length, in which could be observed eye spots. The relative growth formula between shell length (SL) and shell height (SH) was SH = 1.0425SL-27.731 (r$^2$= 0.9749) during the entire larva period. In regard to water temperature, growth and survival rates of larvae were good at 16$^{\circ}C$. Lower growth and survival rates were observed at 12$^{\circ}C$ and 20$^{\circ}C$ than that at 16$^{\circ}C$. When larvae were fed mixed phytoplankters, such as isochrysis galbana, Pavlova lutheri and Chaetoceros calcitrans, their growth and survival rates were the highest among groups.

• Development and Reproduction
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• v.9 no.2
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• pp.95-103
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• 2005

Reproductive cycle, gonadosomatic index(GSI), egg diameter composition, first sexual maturity, sexually matured length(50% of first sexual maturity), and sex ratio of Amusium japonicum japonicum, were investigated by histological observations and morphometric data. Samples were collected monthly from the subtidal zone of Sogwipo, Jejudo, Korea, for two years. The sun and moon scallop Amusium japonicum japonicum is dioecious. Monthly variation in the GSI showed similar patterns with the reproductive cycle. Ripe oocytes were about $70{\sim}90\;{\mu}m$ in diameter and had thick egg membranes. The spawning period was from November to January, and the main spawning occurred between November and December when the seawater temperature was relatively low. From monthly changes in egg diameter composition, the spawning period was once a year, although the number of spawning frequencies is assumed to occur more than twice during the spawning season. The reproductive cycle of this species could be divided into five successive stages: early active stage(April to June), late active stage(June to September), ripe stage(October to November), spawning stage(November to January), and spent/resting stage(February to April). First sexual maturities in female and male scallops ranging from 85.1 to 90.0mm in shell length were over 50% and they were 100% for scallops over 90.0mm in shell length. In this population, sexually matured shell lengths(50% of rate of group maturity) in females and males were 86.96 and 86.59mm, respectively. The female to male sex ratio among individuals over 85.1mm in shell length was not significantly different from 1:1($X^2=0.18$, p>0.05). No evidence of hermaphrodite was found in histological sections of any scallop examined.

• Journal of Aquaculture
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• v.17 no.3
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• pp.180-186
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• 2004

This study was carried out to obtain the fundamental data for the mass seedling production of grunt, Hapalogenys nitens in terms of the natural spawning and some characteristics of the eggs spawned. The wild grunt were reared at indoor tanks for three years. The adults spawners were 34.0∼44.0 cm (38.6$\pm$4.0 cm, n=7) in total length, 1.00∼2.23 kg (1.62$\pm$0.50 kg, n=7) in body weight. Spawning were observed 9 times from September 22 to October 1, 2000 and 37 times from August 22 to October 3, 2001, with a water temperature range of 19.8$\pm$28.5$^{\circ}C$. The total number of eggs collected was 2.29${\times}$10$^{7}$ (1.7${\times}$10$^{3}$/ml). The relative proportion of floating eggs to total eggs was 41.7%. The fertilization rate of floating eggs was ranged between 85.0 and 99.9% and the hatching rate was ranged between 2.9 and 93.0%. Fertilized eggs were buoyant and spherical in shape, and were 0.85∼0.98 mm in diameter. Each egg contained 1-5 oil globules which were, 0.18∼0.25 mm in diameter. The incubation time from fertilization to blastodisc formation was 10 minutes, to blastula was 3 hours, and to the hatched larvae at 26$^{\circ}C$ was 20 hours 30 minutes. The newly hatched larvae attained total length of 1.81$\pm$0.18 mm. The time required from fertilization to hatching was 31∼34 hours at 23$^{\circ}C$ and 17∼20 hours at 29$^{\circ}C$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.5
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• pp.477-483
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• 1985

This paper describes seasonal changes of total length, hepatosomatic index (HSI), fatness, egg-diameter composition, and fecundity of the longchin goby Chasmichthys dolichognathus(HILGENDORF). The specimens used were captured in the tide pool of Tongbaekseom, Pusan, Korea from February 1983 to January 1984. The age of longchin goby, tested by size frequency, was believed to be usually one year which grows to 8.0 cm in total length. The annual variations of HSI reached the maximum in the early spring when the gonad was actively growing and decreased during the spawning season from April to July. The coefficients of fatness were represented low values for the spawning periods. Frequency distribution of the egg diameter of mature ovary has three modes: one is the evident mode of the ripe eggs group, and the other two are modes of maturing and immature eggs groups. And an individual is considered as spawns one in the spawning season. Relationships between the fish size in total length (TL cm) and the number of ovarian eggs(F), the fish weight (BW g) and the number of ovarian eggs are indicated by the exponential equation respectively : F=42.585 $TL^{1.608}$, F= 524.589 $BW^{0.475}$.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.05a
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• pp.282-283
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• 2000

The egg development of various fishes is studied by various methods including electron microscopy(Matsuyama et al, 1991) and hormone treatment(Schoonbee et al. 1980). In addition to attempt to induce final maturation and spawning, the present experiments were conducted to investigate the influence of hCG upon reproductive cycles in catfish(Silurus asotus) with developing gonads and to stimulate the reproductive system during the rapid phase of gonadal development. (omitted)

• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.5
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• pp.351-362
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• 1989

Ecology of Crangon affinis was studied in the Nakdong River Estuary fron June 1988 to May 1989. The growth rate of female was similar to that of male. Size differences, however, were apparent between female and male. Sex ratio varies with season. The major spawning season was from June 1988 to May 1989 except for November 1988. The number of eggs of the largest ovigerous female (35.55mm TL) was over 4,000, while that of the smallest ovigerous female (15.05mm TL) more than 120. The mean number of eggs was 1778. The size of winter eggs is larger than that of the summer eggs. The mean percentage of egg loss from brooding to hatching was $29.06\%$. The rate of egg loss decreases with increasing age. Major component of food organisms includes mysids and polycheates.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.3
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• pp.255-263
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• 2014

We investigated the reproductive characteristics of Lycodes tanakae in the coastal waters of the middle East Sea to elucidate the species' population structure. We investigated Lycodes tanakae maturation and spawning based on samples collected by Danish seine and gill nets from January 2012 to December 2013. We analyzed monthly changes in maturity stage, gonadosomatic index (GSI), egg diameter, fecundity, and total length at 50% group maturity. The spawning period was December to February, while fecundity ranged from 1,677 eggs at 57.3 cm (total length;TL) to 6,445 eggs at 75.7 cm. The relationship between TL and fecundity (F) was $F_e=6E-05TL^{3.127}$ ($R^2$ = 0.516), and F increased with increasing TL. We estimated the TL at 50% group maturity as 60.4 cm for females and 59.8 cm for males. This study is the first report of Lycodes tanakae reproductive characteristics in the coastal waters of the middle East Sea.

• Fisheries and Aquatic Sciences
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• v.10 no.2
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• pp.74-85
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• 2007

Pacific anchovy (Engraulis japonicus) eggs were collected during the spawning season (2000-2003) using a revised ring net in the coastal waters adjacent to the Geum River Estuary in the West Sea of Korea (Yellow Sea). Anchovy eggs were present from May to September, showing a peak in spawning from June to July when the water temperature and salinity were $17-27^{\circ}C$ and above 30.00 psu, respectively. During the main spawning season, no clear diel cycle (regarding the 24-h sampling period of dusk, night, dawn, and daytime) was detected in the vertical distribution of anchovy eggs near Eocheong Island (50-60m depth). Judging from the developmental stages of the collected eggs, it appeared that anchovies spawned mostly at night and that the eggs hatched at dusk and during the night. The density of anchovy eggs was high in the southwest-northeast direction in June, and spawners appeared to move offshore in July. Mean egg density was higher in June 2002 than in June 2003 when water temperatures and salinities were lower. This study on the spatiotemporal distribution of eggs will contribute to developing management plans for the Pacific anchovy in Korea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.1
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• pp.67-73
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• 2020

The maturity and spawning of the yellow goosefish Lophius litulon were studied using samples collected monthly from January to December 2018 from the coastal waters of Korea. We analyzed monthly changes in maturity stage, gonadosomatic index (GSI), total length (TL) at 50%, 75%, and 97.5% group maturity, egg diameter and fecundity. The spawning period was from January to June. The size of eggs spawned was between 0.30 to 1.28 mm. Fecundity varied between 328,314 to 1,624,783 eggs. The percentage of sexually mature females estimated from a logistic function was over 50% at 48.67 cm TL, 75% at 56.76 cm TL and 97.5% at 74.89 cm TL.

• Korean Journal of Ichthyology
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• v.23 no.2
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• pp.158-162
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• 2011

Growth and spawning ecology of Cobitis lutheri (Teleoste: Cobitidae) were investigated in the Samcheon Stream, Mangyeong River, Jeollabuk-do, Korea from 2005 to 2006. Age group of C. lutheri estimated from the total length indicated that the 40 ~ 60 mm group is 1 year old, the 60 ~ 80 mm group is 2 years old, and the 80 ~ 110mm group is 3 ${\leq}$ years old. The sex ratio (Male/Female) was 0.78, and the female was 20 ~ 30 mm larger than the male. Lamina circularis at the base of pectoral fins in the males as a secondary sexual character was created 12 months after hatching. A change of lateral coloration of males was observed from April to September. The spawning season was early to middle July with water temperatures of $24{\sim}26^{\circ}C$. The average number of eggs was $1,127{\pm}453$ with the egg diameter of $1.09{\pm}0.02$ mm.