• Journal of Fisheries and Marine Sciences Education
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• v.29 no.2
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• pp.409-414
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• 2017

Effects of human chorionic gonadotropin (HCG) on ovulation and spawning of the grass puffer, Takifugu niphobles, were investigated. Matured females spawned successfully by all doses of HCG. Spawning usually occurred 24 hours after hormone injection. Body weight of adult, gonadsomatic index (GSI), pseudo-GSI, body weight of spawned egg, success rate of spawn, fertilization rate, hatching rate, and survival rate of juvenile were correlated with increasing HCG doses. However, abnormal rate of juvenile was not correlated with increasing HCG doses. These results should be useful for developing aquaculture program of grass puffer.

• Development and Reproduction
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• v.17 no.3
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• pp.247-255
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• 2013

The gonadsomatic index (GSI) of mottled skate was the highest in April, GSI and HSI showed a reverse phase for its reproductive cycle. The fish had one pair of egg capsules, having 1 to 7 fertilized eggs, and spawned all the year round. When surveying the reproductive characteristics of females over 63 cm in disc width, we found the spawning peak was between April to June, and the appearance ratio of egg capsules was the highest in May (32.1%). The eggs were hatched at $8^{\circ}C$, $13^{\circ}C$, $18^{\circ}C$, water temperature (12.8 to $24.2^{\circ}C$), and the best hatching temperature was $18^{\circ}C$. The number of fish hatched was 4 to 5 fish/egg capsules, and the hatching rate was 100%. The sex ratios of hatching larvae were 45.5% female and 54.5% male. Therefore this study will provide fundamental data and information for artificial reproduction of the mottled skate.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.3
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• pp.253-258
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• 2002

The androgenic gland secretes a hormone, androgenic gland hormone, which is believed to act on the differentiation of the primary, secondary, and behavioral sex characteristics in most malacostracan crustaceans. Based on the changes in gonado-somatic indexe and histological observation of testis and androgenic gland cell, testicular maturation and spermatogenesis of M. nipponense occurred early in summer (May to July), and generally spermatogenesis was absent in August. It could be, concluded that May to July is the period when adult males of this species are sexually active, and androgenic gland showed signs of increased secretory activity.

• Development and Reproduction
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• v.11 no.3
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• pp.155-165
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• 2007

Gonad index (GI), conditon index, the reproductive cycle with gonadal development of the Neptunea (Barbitonia) arthritica cumingii, were investigated histologically, based on the samples which have been collected from the subtidal zone of Oeyeondo, Boryeong, Korea from January to December, 2006. Neptunea (Barbitonia) arthritica cumingii is dioecious and oviparous. Monthly changes in the gonad index (GI), studied for determination of spawning period, were closely associated with gonad developmental phases. The GI reached a maximum in April, and gradually decreased from May to August due to spawning. The gonadsomatic index and condition index showed similar patterns to gonad developmental phases and the spawning period. The reproductive cycle according to gonad developmental phases of this species can be classified into five successive stages in females and males: in females, early active stage (September to October), late active stage (November to February), ripe stage (February to June), partially spawned stage (May to August) and recovery stage (June to August); in males, the early active stage (September to October), late active stage (November to February), ripe stage (February to June), copulation (April to July), and recovery stage (July to August). Spawning occurred between May to August in females and April to July in males, and spawning peak in females was observed between June and July when the seawater temperature rose to above $19^{\circ}C$. Percentages of first sexual maturity of female and male snails ranging from $50.1{\sim}60.0\;mm$ in shell height were over 50%, and 100% for snails over 60.1 mm in shell height. The sex ratios of females to males were not significantly different from a 1:1 sex ratio.

• The Korean Journal of Zoology
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• v.36 no.2
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• pp.181-192
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• 1993

The spawning and growth of eightspine stickleback,Pungitius sinensis kaiborae (Tanaka, 19151, were investigated in the Chavang Stream from March 1990 to february 1991 as a part of study on its life history. Nest building, spavming and parental behaviors were similar to those known on the sticklebacks of Europe, North America and Japan. Bht f sinensis kaibarae in the Chayang Stream, peculiarly, showed only superficial gluing behavior in nest building phase and made two nurseries iust behind the nest in Parental Phase. The individuals with fully mature eggs were found from late February to late June. The fecundity of an adult female was about 21 to 110 (mean 47.07) eggs and the diameter of kllv matured ovarian eggs ranged 1.3 to 1.5 mm. The smallest female with fully mature eggs was 25.8 mm in body length and had 21 eggs. The relationship between the number of mature eggs in ovary and body length was No. of eggs = 2.857BL -55.134 (r = 0.890). The number of deposited eggs in a nest was 27 to 637 and thew were composed of several clusters of various developmental stages. The distribution pattern of gonadsomatic index (GSl) against the body length shown that in females 1+ year-old fishes mainly participate in spawning but in males 11 and 2+ year-old fishes equally participate. From the fluctuat지n pattern of GSI and the number of mature eggs in ovary, it was assumed that the spawning season was from February to June and the peak of spawning was early March to late April. The newly hatched vouns was found at late April and their body length was about 10 mm. The vouns (O+) grew rapidly until late August. Then their srowth was slowed down and finallY ceased in midautumn. The young reached about 35 mm BL in their first year of life. The halting of growth was lasted to next Sune when the spawning season would be nearly closed. They (1+) began to grow asain from late june, grew rapidly until tate september and reached about 415 mm BL. Then there was no more grouvth until to die as 2+ yearold fish. Therefore it was assumed that the life span of P. sinensis kaibarae in the Chavang Stream would be about ko years. The relationship between the body length and the body weight was logBW = 2.9541ogBL -4.802 (r = 0.998).