• Animal cells and systems
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• v.16 no.1
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• pp.77-84
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• 2012

The objective of the study was to investigate if reproductive characteristics of $Pandalus$ $eous$ affect the depth distribution in the East Sea of Korea. $P.$ $eous$ was found at depths of 500-900 m in the East Sea of Korea, with the highest percentage occurrence (34%) at 500 m. A negative correlation was observed between the number of individuals and the depth. The overall sex ratio also turned out to be significantly correlated with depth. On average, the larger individuals (bigger than 26.37 cm), which included transitional, female, and ovigerous females, were mostly distributed at 700 m depth. The percentage of males increased by depth and ovigerous females were mainly distributed in the shallow water (300 m) during winter. Ovigerous females were not found at 900 m, which is the deepest depth range in this study. The percentage of transitional individuals was greatest at 500 m and decreased gradually with depth. All ovigerous female individuals were of the spent ovarian stage in winter. Female numbers in the ripe ovarian stage increased with depth and immature females rarely appeared. The gonadosomatic indices of the nonovigerous females and ovigerous females were highest at 700 m in depth. The mean egg size of $P.$ $eous$ was $0.83{\pm}0.11mm^3$ in the non-eyed stage and $0.93{\pm}0.17mm^3$ in the eyed stage.

• 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.57 no.1
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• pp.60-68
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• 2024

The size distribution, maturation, and molting stages of the snow crab Chionoecetes opilio in the coastal sea of Gyeongbuk were investigated to understand its monthly and bathymetric occurrence patterns. C. opilio was collected from three depth strata (A1, 100-120 m; A2, 120-180 m; A3, 180-220 m) from May to November 2020. The average sex ratio was 0.8. The mean carapace width was largest in females in October, and in males in November. The occurrence rate of small immature crabs was the highest in A1. The ratio of ovigerous females at 75-80 mm was highest at A2 and A3. There was a significant difference in carapace width in females and depth in both sexes in September and October. The occurrence rate of immature crabs was the highest in A1, whereas that ovigerous and spawned females was higher in A2 and A3 than in A1. Very old-shelled females occurred highly in September and October. The occurrence rate of newly shelled males was higher throughout the study period. This research indicated that the size distribution, maturation conditions, and molting stages of C. opilio varied with water depth strata in the coastal sea of Gyeongbuk, Korea.

• Animal Systematics, Evolution and Diversity
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• v.23 no.2
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• pp.205-208
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• 2007

The first zoeal characters of plagusiine crab Plagusia dentipes De Haan, 1835, belonging to the family Grapsidae, is described and illustrated in detail based on laboratory-hatched material from an ovigerous female collected from Bomok, Seogwipo in the Jejudo Island. Morphological comparison is made with previous description of Plagusia dentipes from Japan. The first zoea of Plagusia dentipes can be readily distinguished from those of two species of Plagusia chabrus and Plagusia depressa by having 2 aesthetascs and 3 simple setae on the antennule, and 8 setae on the coxal endite of the maxilla.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.6
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• pp.670-678
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• 2010

An ecological investigation was conducted in winter from November 2007 to February 2008, around Wangdol Reef in the East Sea to analyze the population structure and fecundity of Chinoecetes opilio. The sex ratio was 30.11:69.89% (female:male) in November, 62.03:37.97% in December, 37.59:62.41% in January and 14.69:85.31% in February. Regression equations indicated highly positive relationships between size and weight parameters (carapace length, width, total weight). During the sampling period ovigerous females were continuously collected. The percentage of ovigerous females was 96% in November, 90.57% in December 89.80% in January, and 88.46% in February. The average number of embryos was 64,800. The regression equation between carapace width and the number of embryos was y = 2.6805x - 0.9182 ($R^2$ = 0.7166). Embryo volume increased as embryo development proceeded. The mean size of an embryo was 0.72 mm. Embryo volume ranged from 0.42 to $0.84\;m^3$ during embryo developmental stages 1 to 3.

• 한국해양학회지
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• v.26 no.2
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• pp.101-107
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• 1991

We report on the seasonal fluctuation of a Poecilostomatoida copepod, Pseudomyicola spinosus associated with the blue mussel, Mytilus galloprovincialis in the Yongsan River estuary (34$^{\circ}$47N, 126$^{\circ}$27'E). P. spinosus has four generations a year, seasonally succeeding each other. The generation that occurs during summer has the highest number of individuals. From June to October with the exception f September, males dominated while female outnumbered from November to May with the exception of January. It is possible to find ovigerous females all year with the exception of February. The largest number of ovigerous females occurs a month earlier than copepodids do. The percentage of C1 to C3 is approximately 4% of the total number of copepodids, indicating that in situ infestation by copepodids mainly occurs in C4 stage.

• Korean Journal of Ichthyology
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• v.7 no.2
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• pp.150-159
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• 1995

First sexual maturity, monthly changes in gonadosomatic index and reproductive cycle of viviparous teleost surfperch, Ditrema temmincki were investigated under photomicroscopy. Samples were collected from May 1992 to August 1993 in the vicinity of Suyoung Bay, Pusan, Korea. Body length at the first sexual maturity in female and male were 12.5cm and 13.5cm, respectively. Gonadosomatic index(GSI) in female reached the maximum in June(just before parturition) and male GSI reached the maximum in October(just before copulation). The testis is composed of a number of seminiferous tubules, and spermatogonia are originated from the germinal epithelium on the seminiferous tubule. The ovary consists of several ovigerous folds, and oogonia are originated from the inner surface of the germinal epithelium within the ovigerous fold. Annual reproductive cycle was classified into the following successive periods : in male, growing period from May to August, maturation period from September to October, copulation period from November to December, and degeneration and resting period from January to April, and in female, growing period from September to October, copulation and maturation period from November to December, gestation period from January to June, and resting period from July to August. Hepatosomatic index(HSI) in male appeared to be negatively correlated with gonadosomatic index, but that in female showed to be positively correlated.

• Journal of Life Science
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• v.9 no.5
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• pp.518-524
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• 1999

Timing of oviposition, nuclear maturation of oocytes, egg-sperm contact and brooding were observed in the giant fresh-water prawn Macrobrachium rosenbergii reared in the laboratory. When a pre-spawning molted female was transferred to the male, the female oviposited commonly at 5 to 10 hr after mating. The first polar body were extruded within 2-3 min after spawning. The egg chromosome progressed to release second polar body by 30 min and mitotic nuclear division occurred in 8 hr after spawning. Thumbtack-shaped spermatozoa were seen peneterating egg membrane with their spike directed forward. Transformation of spermatozoa and fertilization membrane could not be observed by light microscopy. The elapsed hours from oviposition to the end of brooding wee taken in 5-7 hr. Brood size for female 9 cm and 18 cm in body length was estimated to be 10,000~15,000 and 100,000 eggs, respectively and is proportional to the total length of the berried females. The ovigerous females reared at chlorinity of 2.21~4.25$\textperthousand$Cl. showed a normal egg development up to hatching.

• Animal Systematics, Evolution and Diversity
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• v.23 no.1
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• pp.69-74
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• 2007

First zoea of cyclograpsinine crab Chasmagnathus convexus (De Haan, 1835) belonging to the family Varunidae, is described and illustrated in detail based on laboratory-hatched material from an ovigerous female collected in Seumjingang river mouth, southern Korea. Morphological comparison is made with previous description of C. convexus from Japan, The first zoea of C. convexus can be readily distinguished from those of six species of Cyclograpsus intermedius Ortmann, 1894, Helicana japonica (K. Sakai and Yatsuzuka, 1980), Helicana wuana (Rathbun, 1931), Helice tientsinensis Rathbun, 1931, Helice tridens (De Man, 1835), and Pseudohelice quadrata (Dana, 1851), the other known cyclograpsinine species in Korea by having the lateral carapace spine, a pair of dorsolateral processes on the fourth abdominal somite, the exopod of antenna with three setae, and the exopod of antenna as being 24.7% length to the protopod.

• 한국해양학회지
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• v.30 no.2
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• pp.138-146
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• 1995

Present study was performed to describe the growth of Leptochela gracilis (STIMPSON, 1860), the dominant species of the coastal water near Kanghwa Island, Korea. Samples were collected from 1 sampling point by long bag seine net at monthly interval from April 1993 to January 1994 except for August 1993. In the population study of Leptochela gracilis, ovigerous female has appeared from April to September 1993 and the ratio (egg-bearing female/female) showed over 70% from May to July 1993. Female individuals were predominant from May 1993 to January 1994 and it was found that sex ratios were not significantly different between pregnant and non-pregnant period(p>0.05). The population of Leptochela gracilis was divided into 2 types of generation; i) short term generation. and ii) long term generation. Longevity of the long term generation was presumed to vary from 12 to 15 months. In the case of short term generation, spawned by egg-bearing stock of September, however, it was not certain whether they absorbed in the long term generation, thus overcome winter season or die after December by environment factors. The growth in cavalcade length of the long term generation was better fitted to Pauly and Gaschutz model than Von Bertalanffy.