• 한국발생생물학회지:발생과생식
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• 제25권3호
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• pp.145-155
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• 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.

• Ocean and Polar Research
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• 제27권3호
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• pp.351-358
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• 2005

Reproductive condition of the tropical blacklip pearl oyster, Pinctada margaritifera collected during the period July through September 2003 from Chuuk Lagoon, Federated State of Micronesia was investigated using histology. The level of gonad development for each pearl oyster was determined with an average score of five microscopic fields, and the average score was used as the maturity index (ML). All wild pearl oysters collected in July did exhibit fully ripe eggs in their ovaries ($45{\sim}50{\mu}M$ in diameter), indicating that they were ready for spawning. In mid August most wild pearl oysters were in spawning and M1 dropped dramatically from mid- to late September, suggesting that the wild pearl oyster completed spawning during this period. In contrast, the cultivated pearl oysters collected in mid-September held ripe eggs in the ovaries and only a few of them spawned, indicating that gonad maturation of the cultivated pearl oyster was somewhat slower than that of the wild pearl oyster in Chuuk Lagoon during the summer period. Histological analysis also indicated that spawning of the pearl oyster is rather incomplete and they may spawn continuously during summer.

• 한국식품영양과학회지
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• 제28권6호
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• pp.1226-1229
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• 1999

In order to investigate the harvest time for the production of high value added ark shell(Scapharca subcrenata) cultured at the south coast of Korea, the seasonal variations of proximate composition(mois ture, protein, fat, ash and glycogen) in the edible portions of ark shell were measured from December 1994 to December 1995. Moisture contents were the lowest in spring, but the highest in summer season being the spawning season of the S. subcrenata. The other hand, protein contents were a maximum in spring and minimum in summer. In June, just before the spawning season, fat and glycogen content was the highest, and ash content was little changed through a year. After spawning season, glycogen contents, showed decrement. In evaluating the seasonal variation of protein, moisture, and glycogen content in ark shell, the relationships of moisture protein content, moisture glycogen content and glycogen protein content show to be reverse.

• 한국패류학회지
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• 제18권1호
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• pp.9-14
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• 2002

In order to estimate the genetic variability and differentiation in common squid, eleven isozymic loci, coded for nine enzymes detected by starch gel electrophoresis, were scored from nine spawning cohorts in four localities. The expected average heterozygosity ranged from 0.00019 (between II-S$_2$ and Na-W) to 0.00814 (Between Bu-S and Na-W) in nine different spawning cohorts in four localities. A dendrogram, based on genetic distance mentioned, illustrated that nine different spawning cohorts were divided into three groups, similar to the result estimated by their ecological characterizations. From these results, we estimate that the common squid distributed throughout Korean waters will maintain this gene exchange. It is postulated that either the summer or the autumn spawning cohort has developed a local population that is isolated by hydrographic factors.

• Fisheries and Aquatic Sciences
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• 제23권7호
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• pp.19.1-19.14
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• 2020

Three generalized additive models were applied to the distribution of anchovy eggs and oceanographic factors to determine the occurrence of anchovy spawning grounds in Korean waters and to identify the indicators of their occurrence using survey data from the spring and summer of 1985, 1995, and 2002. Binomial and Gaussian types of generalized additive models (GAM) and quantile generalized additive models (QGAM) revealed that egg density was influenced mostly by ocean temperature and salinity in spring, and the vertical structure of temperature, salinity, dissolved oxygen, and zooplankton biomass during summer in the upper quantiles of egg density. The GAM and QGAM model deviance explained 18.5-63.2% of the egg distribution in summer in the East and West Sea. For the principle component analysis-based GAMs, the variance explained by the final regression model was 27.3-67.0%, higher than the regular models and QGAMs for egg density in the East and West Sea. By analyzing the distribution of anchovy eggs off the Korean coast, our results revealed the optimal temperature and salinity conditions, in addition to high production and high vertical mixing, as the key indicators of the major spawning grounds of anchovies.

• 환경생물
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• 제20권3호
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• pp.268-275
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• 2002

Seasonal variation in reproductive condition of the Pacific oyster Crassostrea gigas was investigated from a suspended cultured oyster population in Gosung Bay, South Korea using histological techniques, Gametogenesis of oysters initiated in February when water temperature reached 11 to $13^\circ{C}$. Increase in oocyte size and the number resulting in follicle expansion was observed from March to May First spawning of oysters observed in mid Jun when the surface water temperature reached 22 to $25^\circ{C}$. Spawning activity of oysters extended from mid June to late September with two marked spawning peaks in June and August. Most oysters collected from October to December exhibited few residual eggs in packed follicles exhibiting a typical spent condition. No gametes were observed from December to February from oysters collected in the Bay. Gonadal development of oysters in the Bay seemed to follow a seasonal fluctuation in environmental conditions such as water temperature and food availability in the water column. Spawning of oysters in late June was in part associated with sudden drop in salinity due to vast amount of freshwater input in the Bay after the summer flooding. Sex ratio of oysters was 59.5% male and 39.8% female. Less than 1 percent (0.6%) of the oysters examined were hermaphrodite; few eggs were observed in testis.

• 수산해양기술연구
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• 제33권2호
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• pp.97-108
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• 1997

황해와 동중국해역에서 근해안강망에 의해 어획되는 황아귀의 어획량 변동과 어장 분포, 그리고 산란 생태를 구명한 결과는 다음과 같다. 황아귀는 연중 어획되며, 이중 많이 어획되는 시기는 겨울철, 가장 적게 어획되는 시기는 여름철인 것으로 나타났다. 황아귀의 어장은 황해와 동중국해에 널리 분포하고 있으며, 중심어장은 일향초 주변 해역으로 어획량이 50 M/T 이상, CPUE가 5kg/haul 이상, C.V는 0.6~0.7의 범위로 낮게 나타났다. 황아귀의 산란시기는 3월과 4월경이며, 이때의 산란장은 일향초와 제주도 사이해역에서 형성되는 것으로 추정되었다. 황아귀의 어장은 월별에 따라 이동하는 현상을 나타내었는데, 즉, 겨울에는 황해저층냉수와 대마난류수의 남하로 어장은 제주도 서방해역에 주로 분포한다. 또 산란시기인 3월과 4월경이 되면, 일향초 부근 해역으로 어장이 밀집하지만, 산란이 끝난 5월이후가 되면 수온의 상승과 더불어 어장은 황해와 동중국해역으로 널리 분산되는 것으로 나타났다.

• 한국환경생태학회지
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• 제26권6호
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• pp.876-883
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• 2012

맹꽁이의 번식활동에 영향을 주는 기상요인을 분석하기 위해 2008년부터 2011년까지 4년 동안 제주도 대정읍에 위치한 산란지에서 조사하였다. 분석요인은 강우량, 습도, 온도, 기압, 풍속으로 강우가 있는 날에 산란유무를 가지고 비교분석을 하였다. 분석결과 맹꽁이의 번식활동에 영향을 주는 요인은 강우량, 습도, 기압으로 나타났다. 이 중에서 가장 큰 영향을 주는 요인은 강우량으로 나타났다. 맹꽁이는 많은 비가 내릴 때 산란활동에 참가하는 것으로 나타났으며, 습도와 기압도 번식활동에 어느 정도 영향을 주는 것으로 분석되었다. 온도인 경우는 번식기간이 여름철이므로 이미 번식활동에 필요한 조건을 충족시킨 것으로 판단하였다. 따라서 맹꽁이도 온대지방에서 이루어진 다른 무미류 연구에서와 같이 강우량과 온도의 영향을 많이 받고 있다는 것이 확인되었다.

• Ocean and Polar Research
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• 제40권1호
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• pp.15-22
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• 2018

In the present study, we investigated temporal variation in the reproductive effort and biochemical contents in adult Manila clam Ruditapes philippinarum at Shi-Heung-Ri beach on the east coast of Jeju Island. Gonad-somatic index (GSI), a ratio of the egg mass to the total biomass determined using ELISA increased dramatically from late May to June (7.1% to 19.5%). In mid-July, GSI dropped to 15.1%, indicating spawning on a small scale during this period. GSI also declined dramatically from late August (15.5%) to September (4.3%), suggesting that massive spawning occurred during this period. A positive correlation was observed between clam size and potential fecundity, while potential fecundity ranged between 1.19-8.40 million eggs/clam. Total proteins and lipids in the tissue increased from late spring to mid-summer, coinciding with an increase in GSI. Protein, lipid and carbohydrate contents in the tissue were lowest in January, indicating that clams were suffering from poor nutritional circumstances, which may be associated with poor food supply from the environment. Monthly increase and/or decrease in the body weight were closely related to gonad maturation and subsequent spawning, which was also linked to temporal changes in the contents of protein, lipid and carbohydrates in the tissue.

• 한국발생생물학회지:발생과생식
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• 제25권4호
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• pp.299-303
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• 2021

The ascidian Halocynthia aurantium (sea peach), a marine invertebrate, belongs to the same genus of the phylum Chordata along with the ascidian Halocynthia roretzi (sea pineapple), which is one of the model animals in the field of developmental biology. The characteristics of development and reproduction of H. aurantium are not yet known in detail. In order to find out the spawning period of H. aurantium, we investigated development of the gonads during the annual reproductive cycle. Testis and ovary were both in the bisexual gonads (ovotestes) of H. aurantium, which is a hermaphrodite like H. roretzi. In H. aurantium, the right gonad was longer and slightly larger than the left gonad throughout the year. In each gonad, the number of the testis gonoducts was slightly higher than that of the ovary gonoducts. These features were similarly observed in H. roretzi. However, the number of the testis gonoducts and the ovary gonoducts in each gonad of H. aurantium was about half that of H. roretzi. The gonads of H. aurantium contracted during the winter and summer seasons. The gonads decreased to the smallest size around February, and then started to increase again in March. The gonads were most developed in September of the year. Therefore, it is estimated that the spawning of H. aurantium begins around this period.