• Fisheries and Aquatic Sciences
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• v.8 no.3
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• pp.182-184
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• 2005

We examined the sex ratio, and insemination rate of Parapenaeus fissuroides and Parapenaeus lanceolatus using samples collected near Cheju Island, Korea, in January 2005. Females were more numerous than males in both species, and based on the gonad color pattern, sex ratio, and insemination rate, the spawning period of these shrimps was determined to be during winter.

• Fisheries and Aquatic Sciences
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• v.8 no.4
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• pp.207-212
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• 2005

Directional (sinistral) asymmetry (DA) occurs when the traits of one side of a supposedly bilaterally symmetrical organism differ in a random way from those of the other side. We examined asymmetries in gonadal growth traits within both sexes of hatchery reared ayu, Plecoglossus altivelis. The pattern of the gonadal growth from hatching to 320 days after hatching was a type of DA except for the growth in gonad weight from 140 to 180 days after hatching, although the ovary of the right side tended to exhibit more pronounced DA phenomenon.

• Animal Systematics, Evolution and Diversity
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• v.35 no.3
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• pp.95-104
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• 2019

The family Mesorhabditidae $Andr{\acute{a}}ssy$, 1976 is the most abundant group in Rhabditoidea and occurs all over the world. Over 85 valid species have been reported from Mesorhabditidae; however, only 2 species have been recorded in South Korea. In this study, Bursilla vernalis $Andr{\acute{a}}ssy$, 1982, Mesorhabditis inarimensis (Meyl, 1953) Dougherty, 1955, and M. minuta $Bostr{\ddot{o}}m$, 1991 belonging to the family Mesorhabditidae (Rhabditomorpha), are newly reported from South Korea. Species in this family are distinguished from other rhabditomorphs by a posteriorly located vulva and an unpaired prevulval female gonad. Details of the morphological characters and morphometrics of B. vernalis, M. inarimensis, and M. minuta are described and illustrated based on optical and/or scanning electron microscopy.

• Journal of Aquaculture
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• v.7 no.4
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• pp.189-205
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• 1994

Formerly, adult-tiger puffer, Takifugu rubripes with ova caught in the sea, were used for seedling production. But it was difficult to secure naturally-ripened adults. For the purpose of adult tiger puffer in captivity, this study was carried out. To determine the growth 220 tiger puffers hatched in 1990 (3-year-old) and 1991 (2-year-old) were used. For spawning and egg incubation leading to fry development, eggs were stripped from tiger puffers hatched in 1988 (5-year-old) and 1990 (3-year-old) through human chorionic gonadotropin (BCG) treatments. In May, 1993, mean body length and mean body weight of 2-year-old tiger puffer were $30.72\pm1.35cm\;and\;1,048\pm228 g,$ and that of 3-year-old tiger puffers were $36.02\pm1.17cm$ and $1,402\pm66g$ respectively. The relationship between body length (L) and body weight (W) of 2-year-old the tiger puffers during the experiment period was represented as $W\;=\;1.7892L^{31524}\times10^5$ (r= 0.9436) and that of 3-year-old, $W=\;3.2840L^{36099}\times10^6$ (r= 0.9070) respectively. The GSI in female 2-year-old-fish changed from $0.23\times0.l2\;to\;0.74\pm0.08$, during the experiment period, and in male it didn't change remarkably until November, but thereafter it increased and showed a peak of $8.69\pm5.09$. The GSI of 3-year-old-fish showed a peak of $8.05\pm5.58$ in April in female and $12.65\pm4.60$ in May in male. The change of HSI in 3-year-old-fish was correlative to the change of GSI, but in 2-year-old-fish it was little correlative. In female gonad of 2-year-old tiger puffer, the mature oocytes reached $350{\mu}m$ in April, but thereafter they didn't spawn and became atrophied. But in male gonad, a great number of spermatozoa were crowded in the testicular lobuli in April. Female gonad of 3-year-old tiger puffer had the mature oocytes of 650 pm in March and the ripe oocytes, $900{\mu}m$ in April. Male testis development was similar to that of 2-year-old-fish. Egg-stripping after hormone treatments was possible past 139 hours and 142 hours from each of two 5-year-old-fish (500IU/kg, BW), and after 114 hour from a 3-year-old-fish (1,000 IU/kg, BW) under water temperature $16.3\~17.8^{\circ}C$. Eggs stripped amounted was 650 g and 400 g from two 5-year-old-fish and 610 g from the 3-year-old-fish, and fertilization rates were $98.0\%,\;97.4\%\;and\;96.5\%$ respectively. All the hatched larvae devloped into normal fry.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.13 no.4
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• pp.179-183
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• 1980

The efficiency of energy transfer by a population of the farmed pacific oyster, Crassostrea gigas was studied during culture period of 10 months July 1979-April 1980, in Geoje-Hansan Bay near Chungmu City. Energy use by the farmed oyster population was calculated from estimates of half-a-month unit age specific natural mortality rate and data on growth, gonad output, shell organic matter production and respiration. Total mortality during the culture period was estimated approximate $36\%$ from data on survivor individual number per cluster. Growth may be dual consisted of a curved line during the first half culture period (July-November) and a linear line in the later half period (December-April). The first half growth was approximated by the von Bertalanffy growth model; shell height, $SH=6.33\;(1-e^{0.2421(t+0.54)})$, where t is age in half-a-month unit. In the later half growth period shell height was related to t by SH=4.44+0.14t. Dry meat weight (DW) was related to shell height by log $DW=-2.2907+2.589{\cdot}log\;SH,\;(2, and/or log $DW=-5.8153+7.208{\cdot}log\;SH,\;(5. Size specific gonad output (G) as calculated by condition index of before and after the spawning season, was related to shell height by $G=0.0145+(3.95\times10^{-3}{\times}SH^{2.9861})$. Shell organic matter production (SO) was related to shell height by log $SO=-3.1884+2.527{\cdot}1og\;SH$. Size and temperature specific respiration rate (R) as determined in biotron system with controlled temperature, was related to dry meat weight and temperature (T) by log $R=(0.386T-0.5381)+(0.6409-0.0083T){\cdot}log\;DW$. The energy used in metabolism was calculated from size, temperature specific respiration and data on body composition. The calorie contents of oyster meat were estimated by bomb calorimetry based on nitrogen correction. The assimilation efficiency of the oyster estimated directly by a insoluble crude silicate method gave $55.5\%$. From the information presently available by other workers, the assimilation efficiency ranges between $40\%\;and\;70\%$. Twenty seven point four percent of the filtered food material expressed by energy value for oyster population was estimated to have been rejected as pseudofaeces : $17.2\%$ was passed as faeces; $35.04\%$ was respired and lost as heat; $0.38\%$ was bounded up in shell organics; $2.74\%$ was released as gonad output, $2.06\%$ was fell as meat reducing by mortality. The remaining $15.28\%$ was used as meat production. The net efficiency of energy transfer from assimilation to meat production (yield/assimilation) of a farm population of the oyster was estimated to be $28\%$ during culture period July 1979-April 1980. The gross efficiency of energy transfer from ingestion to meat production (yield/food filtered) is probably between $11\%\;and\;20\%$.

• Development and Reproduction
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• v.4 no.2
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• pp.195-201
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• 2000

Sex differentiation process of the spotted sea bass, Lateolabrax maculatus, was investigated by histological method. The fish samples were collected from just after hatching to 365 days later. The primordial germ cells and genital ridge were appeared separately hanging under air bladder in 30-day larva (total length: 11.7~13.2 mm), and were unified into the undifferentiated gonads in 40-day larva (12.5~14.0 mm). The ovarian differentiation was started in 60-day juvenile (23.6~27.0 mm). The somatic tissues were elongated in tip of both ends of undifferentiated gonad and were fused each other. The complete ovarian cavity was appeared in 80-days juvenile(33.1~42.5 mm). The testicular differentiation was initiated in 70-day juvenile (24.8~31.6 mm). The rudiment of sperm duct was appeared in the center of the undifferentiated gonad. The meiosis of germ cells in the ovary was started in 168-day juvenile (88.0~115.4 mm). In 287-day juvenile (175.1~233.6 mm), the ovary was filled with both of chromatin stage and perinucleolus stage oocytes. The meiosis of male germ cells was started in 245-day juvenile (124.4~168.3 mm). However, the seminiferous tubules of testis were filled with numerous sperm in 365-day juvenile (162.5~253.8 mm). The sex ratio of male and female was 1:1.38. Considering these results, the spotted sea bass was showed differentiated type in sex differentiation and gonochorism in sexuality.

• Journal of Aquaculture
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• v.19 no.4
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• pp.315-322
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• 2006

The objective of the present study was to investigate the expression of heat shock protein 90 (HSP90) and 70 (HSP70) mRNA as cellular stress responses, the levels of plasma cortisol with glucose as neuro-endocrine stress responses during water temperature rising in freshwater adapted black porgy, Acanthopagrus schlegeli. A cDNA fragment of 891 (HSP90) and 465 (HSP70) bp was cloned from black porgy testis by Reverse transcription-polymerase chain reaction (RT-PCR) with primers designed from the conserved regions of other teleost. The PCR product of HSP90 showed very high homology to red seabream (99%), rainbow trout (95%), Atlantic salmon (94%), zebrafish (94%) HSP90, HSP70 of black porgy was also highly similar to those of rainbow trout (96%), silver seabream (95%), zebrafish (95%) HSP70. Water temperature rising ($20{\sim}30^{\circ}C$) induced elevation of HSP90 mRNA in black porgy gonad, liver, brain, intestine and kidney, whereas it resulted in an induction of the HSP70 mRNA expression in gonad only. Plasma cortisol levels increased significantly at $30^{\circ}C$ in the fish compared to those at $20^{\circ}C$. Glucose levels of the fish showed a tendency of co-increase with cortisol during water temperature rising. These results suggest that increased HSP90 mRNA in liver with plasma cortisol following heat shock may be related to increasing glucose for homeostasis in this species.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.4
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• pp.627-633
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• 1997

Gonad structure, germ cell development and reproductive cycle of the smallmouth scorpionfish, Scorpaena miostoma were investigated based on histological method. Samples were collected monthly in the vicinity of Suyoung Bay, Pusan, Korea from November 1995 to October 1996. The testis is seminiferous tubule type in internal structure. Seminiferous tubule consists of numerous testicular cysts which contain numerous germ cells in same developmental stage. The ovary consists of several ovarian lamellae originated from ovarian outer membrane. Oogonia originated from the inner surface of the ovarian lamella protrude to the ovarian cavity in oocyte stage, and they are suspended by the egg stalk. Biological minimum size of female and male were 12.5cm in total length. Gonadosomatic index (GSI) of female (3.81) and male (0.23) were the highest in October. Reproductive cycle was classified into the following successive stages: in female, growing stage $(May\~August)$, maturation stage $(September\~October)$, ripe and spawning stage $(November\~December)$, recovery and resting stage $(January\~April)$, and in male, growing stage $(June\~August)$, maturation stage $(September\~October)$, ripe and spent stage $(November\~January)$ and recovery and resting stage $(February\~May)$.