• Journal of Aquaculture
• /
• v.18 no.1
• /
• pp.1-6
• /
• 2005

This study focused on spawning season, induce spawning, spawning and larval development of the Jicon scallop in Daehuksan Island of southwestern waters in Korea. The condition index and gonadosomatic index were used to investigate the reproductive pattern of the Jicon scallop. The major spawning season was from July to August, showing an unimodal gametogenic cycle per year. Several different tests were carried out to induce spawning of the mature male and female C. farreri. For females, the injection of serotonin, temperature induction technique and the combination of the both treatments produced significantly faster gamete release. Unlike females, males spawned only in response to the UV rays irradiation stimulation. Mean size of fertilized eggs was 69.5 $\mu$m in diameter. After fertilization, the zygote could be divided into 2 cells as early as 2 hours. It took about 8 hours to develop the 8-cell stage, about 20 hours to hatch trochophore larvae, and about 40 hours to be D-shaped larvae.

• Korean Journal of Ichthyology
• /
• v.31 no.3
• /
• pp.141-149
• /
• 2019

This study presents data on spawning season, weight-length relationships (WLRs) and condition factor of Gadus chalcogrammus inhabiting the middle East Sea, Korea. Monthly changes in the gonadosomatic index (GSI) revealed that the spawning period was from December to March. Overall value of the exponent b, estimated by nonlinear least squares from weight and length data was 2.806, ranging from 2.778 for female fishes to 2.985 for immature group. The b values were similar between spawning and non-spawning, and between female and male fishes, but it was significantly higher for immature than mature fishes. The condition factors were significantly higher for immature than mature groups, and during non-spawning than spawning periods, but it was not significant between male and female fishes.

• Fisheries and Aquatic Sciences
• /
• v.7 no.3
• /
• pp.136-140
• /
• 2004

We examined the ovaries of 312 robust tonguefish (Cynoglossus robustus) collected each month from January to December 2001, off the coast of Yeosu, Korea. The samples were used to investigate robust tonguefish reproductive activity. Monthly changes in the gonadosomatic indexindicated that spawning peaked between June and August. Fish size at first spawning was 15-19 cm total length (TL). Over $50{\%}$ of female fish 25-29 cm TL were sexually mature, and this rose to $100{\%}$ for female fish 35-39 cm TL. The tonguefish spawned four or more times during the spawning season. Most females commenced spawning in their second year. The relationship between total length (cm TL) and fecundity (F) was F=528646Ln(TL)-1E+06.

• The Korean Journal of Zoology
• /
• v.8 no.2
• /
• pp.67-72
• /
• 1965

The breeding season of the bivalve, Lamprotula coreana , was observed in the vicinity of Achun-Ri of the Han River under the natural conditions. The effect of temperatures on spawning and attaching periods of the glochidia was also investigated in the laboratory. 1. The breeding season of Lamprotula coreana was lasted from October to April in the next year. The glochidia of Lamprotula coreana were observed in the outer gill layers, therefore they beling to the exobrachiae. 2. Each spawning of glochidia of Lamprotula coreana ended within 15, 12 , 7 and 5 days at 1$0^{\circ}C$, 15$^{\circ}C$, 2$0^{\circ}C$ and $25^{\circ}C$of water temperatures respectively. 3. The attaching period of glochidia of the Lamprotula coreana onto fish was longer at a low temperature than at higher one.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.46 no.6
• /
• pp.835-842
• /
• 2013

Flathead flounder Hippoglossoides dubius is a commercially important fish in the coastal waters of Gangwon Province, which is its spawning ground and breeding habitat. A total of 1,669 gonads were sampled monthly from February 2011 to May 2013 to investigate ecological characteristics, such as variations in maturation and spawning by gonad index, visual maturity stage, histological observations and oocyte diameter. Males were numerically dominant over females in the fishing grounds year round. The spawning season was from January to April, and the peak was from February to March. Oocyte number as a measure of fecundity was between 27,372 and 915,209 eggs with a length range of 26.0-48.7 cm TL, while the largest oocyte grew to 0.9-1.4mm in egg diameter during its spawning season. The relationship between fecundity and total length was $F=0.0016TL^{5.2539}$. The smallest mature lengths of the females and males were 28.4 and 22.6 cm respectively, and the 50% mature lengths of females and males were 32.9, 26.9 cm respectively.

• Development and Reproduction
• /
• v.25 no.3
• /
• pp.145-155
• /
• 2021

Reproductive cycle of the blue-striped angelfish, Chaetodontoplus septentrionalis were histologically investigated. Fish were monthly collected in the coastal waters of Munseom, Seogwipo, Jeju-Island from February to December 2018. The gonadosomatic index (GSI) increased from May and maintained high values in August. The reproductive cycle of female fish can be classified by the characteristics observed during gonadal development as followed: growing stage (November to June), early mature stage (May to June), mature and spawning stage (June to September), and degenerative and recovery stage (September to December). In the male, testicular development period was similar to that of ovarian development period, but mature and spawning period was one month longer from June to October. Fecundity of mature female ranged from 4,601 to 22,840 and was correlated positively with total length and body weight. The histological analysis of gonadal development indicated that the C. septentrionalis was summer-spawning type and is considered a multiple spawner during spawning season.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.7 no.4
• /
• pp.215-220
• /
• 1974

The sand-eel, Ammedytes Personatus is a commercially important fish abounantly found in west and east coast of Korea. Samples were collected from the Baegryeong Island (Yellow Sea), Geoje Island(southern coast) and Jumunjin (East Sea) from May 1973 to December 1974. In this paper the author dealt with some biological point of the fish, especially the relationship between total length ang body weight, and the major spawning season and sex ratio. 1. The major spawning season was confined to the end of November and the end of December at Jumunjin. 2. The sex ratio (male/female) is 0.75 before the main spawning season and increases up to 1.36 after spawning at Jumunjin in 1974. 3. The relationship between the total length (L) and body weight (In were represented as follows: $W=0.0001906L^{3.1998319}$ for the sample from Baegryeong Is. $W=0.0003419L^{3.0213438}$ for the sample from Geoje Is. $W=0.0002655L^{3.1408629}$ for the sample from Jumunjin.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.19 no.3
• /
• pp.103-119
• /
• 2016

This study aims to assess habitat feature on the large-scale spawning ground of the Boreal Digging Frog Kaloula borealis in Daemyung retarding basin of Daegu, and to analyze the relationships between species abundance and meteorological factors for each habitat. Fifty-seven(57) pitfalls were installed to collect species abundance of 4 survey regions, and high-resolution satellite image, soil sampling equipment, digital topographic map, and GPS were used to develop habitat features such as terrain, soil, vegetation, human disturbance. The analysis shows that the frog is most abundant in sloped region with densely herbaceous cover in southern part of the retarding basin. In the breeding season, lowland regions, where Phragmites communis and P. japonica dominant wetlands and temporary ponds distributed, are heavily concentrated by the species for spawning and foraging. Located in between legally protected Dalsung wetands and lowland regions of the retarding basin, riverine natural levee is ecologically important area as core habitat for Kaloula borealis, and high number of individuals were detected both breeding and non-breeding seasons. Temperate- and pressure-related meteorological elements are selected as statistically significant variables in species abundance of non-breeding season in lowland and highland regions. However, in sloped regions, only a few variables are statistically significant during non-breeding season. Moreover, breeding activities in sloped regions are statistically significant with minimum temperature, grass minimum temperature, dew point temperature, and vapor pressure. Significant meteorological factors with habitat features are effectively applied to establish species conservation strategy of the retarding basin and to construct for avoiding massive road-kills on neighboring roads of the study sites, particularly post-breeding movements from spawning to burrowing areas.

• Development and Reproduction
• /
• v.16 no.3
• /
• pp.205-217
• /
• 2012

The ovarian cycle, the biological minimum size, and artificial spawning frequency by artificial spawning induction of the female hard clam, Meretrix petechialis, were investigated by histological observations and morphometric data. The ovarian cycle of this species can be classified into five successive stages: early active stage, late active stage, ripe stage, partially spawned stage, and spent/inactive stage. The spawning period was from June to September, and the main spawning occurred between July and August when the seawater temperature exceeds over $20^{\circ}C$. The biological minimum size (shell length at 50% of first sexual maturity) in females were 40.39 mm in shell length (considered to be two years of age), and all clams over 50.1 mm in shell length sexually matured. In this study, the mean number of the spawned eggs by spawning induction increased with the increase of size (shell length) classes. In case of artificial spawning induction for the clams > 40.39 mm, the number of spawned eggs from the clams of a sized class was gradually decreased with the increase of the number of the spawning frequencies (the first, second, and third spawning). In the experiments of artificial spawning induction during the spawning season, the interval of each spawning of this species was estimated to be 15-18 days (approximately 17 days).

• The Korean Journal of Malacology
• /
• v.21 no.2 s.34
• /
• pp.81-93
• /
• 2005

Reproductive cycle with the gonadal phases, first sexual maturity, artificial spawning amount by the size and spawning interval of the hard clam, Meretrix lusoria were investigated by histological observations and morphometric data by artificial spawning induction. Meretrix lusoria is dioecious and oviparous. The reproductive cycle of this species can be classified into five successive stages: early active stage (January to March), late active stage (February to May), ripe stage (April to August), partially spawned stage (June to September), and spent/inactive stage (September to February). The spawning period was from June to September, and the main spawning occurred between July and August when the seawater temperature exceeds over $20^{\circ}C$. Percentage of first sexual maturity of female and male clams ranging from 40.0 to 45.0 mm in shell length was over 50%, and all clams over 50.0 mm in shell length sexually matured. Female and male clams ranging from 40.0 to 45.0 mm in shell length are considered to be two years old. Therefore, we assume that the hard clams of both sexes begin reproduction from two years of age. The mean number of the spawned eggs increased with the increase of size (shell length) classes. In case of artificial spawning induction, the number of spawned eggs from the clams of a sized class was gradually decreased with the increase of the number of the spawning frequencies (the first, second, and third spawnings). In the experiments of artificial spawning induction during the spawning season, the interval of each spawning was estimated to be 15-18 days (average 17 days).