• Fisheries and Aquatic Sciences
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• v.21 no.11
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• pp.34.1-34.13
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• 2018

Sexual maturity ($L_{50}$), the length at which 50% of fish in a size class are mature, is a key aspect of domestication of new fish species because it guides the procedure for identification of appropriate broodstock size for artificial spawning. In this study, the $L_{50}$ was determined for 1083 Barbus altianalis samples obtained from Lake Edward and the Upper Victoria Nile. Gonads of freshly killed samples were examined macroscopically and verified with standard histological procedures for the maturation stages that were used to determine $L_{50}$. Oocytes and spermatogenic cell sizes were compared for fish obtained from both water bodies. Results indicated that there were no variations in macro gonad features observed for fish from Lake Edward and Upper Victoria Nile. Similarly, there were no significant differences in oocyte sizes (P > 0.05) between the two populations but significant differences in spermatogenic cell sizes were noted (P < 0.05) except for spermatozoa (P > 0.05). This however did not suggest peculiar differences between the two populations for staging the gonads. Consequently, no staging variations were suggested for both populations in determination of $L_{50}$. Sexual maturity was found in the same class size of fork length (FL) 20-24.9 cm and 35-39.9 cm for males and females from both water bodies, respectively. At this FL, however, males were too small, and for good selection of vigor broodstocks for spawning and conservation purposes, they are better picked from class size of 30-34.9 cm FL and above. These findings were crucial for integration of appropriate breeding size in spawning protocol by farmers and fisheries scientists conserving wild B. altianalis populations.

• Journal of Practical Agriculture & Fisheries Research
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• v.21 no.1
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• pp.149-157
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• 2019

This study interested on management of broodstock and the effect of raise the temperature for promotion of maturity in Tresus keenae. For management of broodstock, we performed indoor and outdoor culture. In addition, broodstock was put in exposure and immersion condition. This experimental design is aimed at knowing the optimal management of broodstock. In addition, we investigated the promotion of maturity, growth and survival rate when raise the temperature of the breeding seawater of broodstock in winter season. Result that, the management of broodstock was shown to be more effective obesity and survival rate in outdoor culture than indoor culture. In addition, there is no anthropogenic food supply in management and it is easy to management because it is kept under natural environmental conditions. Therefore, It is considered appropriate to management to outdoor culture. In raise the temperature, survival rate was lower in the experimental group than in the control group. However, obesity was significantly increased compared with the control group. Also, gonad showed that the sex maturity was promoted. If sex maturation is not developed due to seasonal water temperature, the promotion of sexual maturity through heating is considered to be an effective method in terms of artificial seed production.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.1
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• pp.19-24
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• 2007

Covariance components and genetic parameters of weekly live body weight from hatching to six weeks of age and age of sexual maturation were estimated in a laying type Japanese quail line. The univariate and bivariate animal model analysis included hatching group and sex as fixed effects. Each trait was analysed with animal as random effect to fit the additive direct effect. Additional random effects incorporated in the models were changed according to the trait examined. The best model for a trait was chosen based on a likelihood ratio test, comparing the models with and without maternal additive genetic and maternal permanent environmental effects. Heritability estimates of live-weight at hatch and one to six weeks of age with their standard errors were 0.22${\pm}$0.088, 0.39${\pm}$0.099, 0.31${\pm}$0.086, 0.38${\pm}$0.056, 0.46${\pm}$0.055, 0.50${\pm}$0.059, and 0.56${\pm}$0.062, respectively. Direct heritability value of age of sexual maturation was moderate (0.24${\pm}$0.055). The variances due to permanent environmental effect of dam after one week of age and maternal genetic effect after two weeks of age were not important sources of variation. The correlations between direct and maternal genetic effects were negative and ranged from high to moderate values (-0.21 to -0.83). Among the weekly live weights, genetic correlations were generally high between not only successive but also early and late weightings. It suggests that selection for final weight may be based on early weight records. Genetic correlations between age of sexual maturation and live weights were low, favourable but had high standard errors. These results indicate that selection for high weight will potentially result in lower age of sexual maturation only with accurate determination of breeding values.

• Fisheries and Aquatic Sciences
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• v.1 no.1
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• pp.82-93
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• 1998

Monthly changes of the gonad follicle index (GFI), reproductive cycle, egg-diameter composition, first sexual maturity of the Pacific oyster, Crassostrea gigas, were studied based on the samples which have been collected from the intertidal zone of Poryong west coast of Korea, from January to December, 1996. C. gigas, is dioecious, while a few individuals are alternatively hermaphroditic. Monthly variation of gonad follicle index (GFI) used for determination of spawning period, coincided with the reproductive cycle. GFI increased from April when seawater temperatures gradually increased and reached the maximum in May. And then, GFI sharply decreased from June to September due to spawning. Reproductive cycle of this species can be divided into five successive stages: in females, early active stage (March to April), late active stage (April to May), ripe stage (May to August), partially spawned stage (June to September) and spent/inactive stage (September to February); in males, early active stage (February to March), late active stage (April to May), ripe stage (May to September), partially spawned stage (June to September) and spent/ inactive stage (September to February). The diameter of fully mature eggs are approximately 50um. Spawning occurred from June to September, and two spawning peaks were observed in June and August when the seawater temperature was above $20^{\circ}C$. Percentages of the first sexual maturity of males of 20.1-25.0 mm in shell height were over $50\%$, while those of females of 25.1-30.0 mm in shell height were over $50\%$. All the males of > 30.1 mm and all the females of ^gt; 35.1 mm completed their first sexual maturity. The results suggest that C. gigas has a protandry phenomenon. Sex ratios of 919 oysters observed were 453 females $(49.29\%)$, 429 males $(46.68\%)$, 16 hermaphrodites $(1.74\%)$, and 21 indeterminate individuals $(2.29\%)$. In age class I, sex ratio of males were $64.00\%$, thus, a higher percentage than that of females. It was noted that $64.00\%$ of the young males (age class I) were more functional than females in age class I, but 2-3 year-old oysters showed higher percentage of females. Percentages of hemaphrodites in 2-3 year classes were relatively higher than those in other year classes. Histological pattern of hermaphrodites can be divided into two types: Type I (hermaphrodite having a number of newly formed developing oocytes on the oogenic tissues within a degenerating spermatogenic follicle after discharge of numerous spermatozoa) and Type II (hermaphrodite having two separate follicles in the same gonad).

• Journal of Sasang Constitutional Medicine
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• v.29 no.2
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• pp.174-181
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• 2017

Objectives Five cases of early puberty patients were diagnosed and treated according to Sasang constitutional medicine. Methods Seven year-old girl and four nine year-old girls visited the children's development clinic and were diagnosed as Sasang constitutional types according to clinical investigations. Their breast stages were in the 2nd degree of SMR(sexual maturity rating). Three were Taeeumin and two were Soeumin, so they were prescribed according to their Sasang constitutional types and complaints. Results and Conclusions It could show that early puberty patients can be given treatments and managements according to Sasang constitutional medicine.

• Animal cells and systems
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• v.13 no.1
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• pp.83-89
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• 2009

Investigations were made on population biology of Pampus echinogaster (Basilewsky, 1855) in the coastal areas of Korea, Yellow Sea, between August 2005 and July 2006. Population structure was not significantly different between male and females. Monthly variation of gonadosomatic index (GSI) of both sexes defined spawning period extending from March through July. A similar pattern was also observed in change at maturity stages. For males and females GSI was positively correlated with hepatosomatic index (HSI). Fecundity, ranging from 41,250 to 103,610 eggs, was related to body size, indicating that body size is the useful determinant of fecundity. The sexual maturity ($L_{50}$) was estimated as 14.98 cm TL for males and 19.32 cm TL for females. Parameters of growth estimated by the modified von Bertalanffy growth function model showed that the values of $L_{\infty}$ and K for combined data were 39.12 cm TL and 0.65 $yr^{-1}$. The growth performance index of this study (2.75) was higher than that of the previous study (2.45). This difference could be attributed to sampling method. The recruitment patterns indicated one normally distributed group. Percentage of the recruitment was 51.04% in the spawning season and the highest in August (19.78%).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.1
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• pp.1-8
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• 2020

The reproductive biology of largehead hairtail Trichiurus japonicus, from near Jeju Island, Korea was investigated based on 4,384 individuals collected by commercial vessel from November 2016 to October 2019. There were more female specimens than male specimens (2.64:1). T. japonicus preanal lengths (PL) ranged from 10.5 to 53.5 cm; the relationships between PL and body weight (BW) were BW=0.0103PL^3.1293 for females and BW=0.0106PL^3.1251 for males. Monthly changes in gonadosomatic index were analyzed to estimate spawning season. The spawning period ranged from June to November. The size-frequency distribution of eggs suggested that T. japonicus exhibits multiple-spawning during a spawning period. The minimum size of females at maturity was 18.2 cm, while the size at sexual maturity was 25.0 cm.

• Korean Journal of Community Nutrition
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• v.4 no.2
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• pp.157-165
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• 1999

This study was conducted to identify the determinants of regional body fat distribution of obesity(upper body obesity and lower body obesity) for adolescents. The macronutrient consumption pattern utilized the most important variables to test for potential determinants. A total of 726 adolescents living in rural areas in Korea had been observed for four years from 1992 to 1996 about their diet, sexual maturation, serum components and physical growth. The study design was similar to that of a case control study. Logistic regression analysis were used as an analytical method to identify the determinants of upper body obesity and lower body obesity. Odd ratios were estimated from the regression to identify the determinants of upper body obesity and lower body obesity. Odd ratios were estimated from the regression to identify the risk factors. Fat consumption pattern was the most frequent one among the three macronutrient consumption pattern of carbohydrate, fat and protein. Prevalence of obesity for the subjects was 9.5%. Prevalence of upper body obesity was higher in malestudents than in female students. On the other had, prevalence of lower body obesity was higher in females. The results of the logicstic regression analysis showed that the risk factor for upper body obesity was sexual maturity rather than dietary factors. None of the factors included in the analysis for lower body obesity appear to be the risk factor. The result may suggest that to develop a determinant model for obesity of adolescents, the model should include a wider range of variables other than diet, sexual maturity and changes in blood serum.

• The Korean Journal of Malacology
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• v.4 no.1
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• pp.30-41
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• 1988

The gonadal development, the annual reproductive cycle and the first sexual maturity of surf clam, Mactra veneriformis Reeve were studied histologically. Speciemens were monthly collected at the intertidal zone of Naechodo, Chollabuk-do, Korea, for one year from March 1986 to February 1987. Sexuality of the clam is dioecious. The gonads were located between the subregion of mid-intestinal gland in the visceral cavity and the reticular connetive tissues of the foot, The ovary is composed of a number of ovarian sacs, and the testis comprise several testiculat lobules. The undifferentiated mesenchymal tissues and eosinophilic granular cells function as nutritive cells in the early stage. The ripe eggs were about 50-60${\mu}{\textrm}{m}$ in diameter, and they were wurroundedby the gelatinous membranes. The spawing period was from early June to September the main spawning occurred beetween July and August when the water temperature reached above 24$^{\circ}C$. The annual reproductive cycle of this species could be classified into five successive stages: multiplicative(January to March), growing(March to May), mature(April to August), spent(June to September), degenerative and resting(September to February). The monthly changes of fatness coefficient closely correlated with the annual reproductive cycle. Percentages of the first sexual maturity of female and male clams were over 50% among those individals ranging from 2.1 To 2.5cm, and 100% in those over 2.6cm in shell length.

• Fisheries and Aquatic Sciences
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• v.4 no.4
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• pp.208-218
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• 2001

We have investigated the gonad index (GI), gonadal development, reproductive cycle, first sexual maturity, sex ratio, the number of spawned eggs and spawning frequency of the Manila clam, Ruditapes philippinarum. Samples were collected from the intertidal zone of Komso Bay, Korea from January to December in 1999. Monthly changes in the gonad index (GI) and condition index showed a similar pattern in the reproductive cycle. The spawning period was once a year between early June and early October, there was a spawning peak between July and August when seawater temperature was over $20^{\circ}C$. The reproductive cycle of this species can be categorized into five successive stages; early active (February to March), late active (April to May), ripe (April to August), partially spawned (June to October), and spent/inactive stage (August to March). Percentages of first sexual maturity of female and male clams of l5.1-20.0mm in shell length were $56.3\%$ and $60.0\%$, respectively, and $100\%$ for the clams >25. mm. The sex ratio of individuals >15.1 mm in shell length was about 1:1 $(\chi^2= 0.02,\;p>0.05)$. Number of the eggs released from each clam by the induction increased as the size of clam in terms of shell length increased. Mean number of the eggs from the second induction of the spawning was $75.35-84.30\%$ $(average\;79.81\%)$ of the number of the eggs released in the first spawning. Our data indicated that R. philippinarum in Komso Bay has one major spawning peak with over two minor spawning, and the interval of each spawning was estimated to be approximately 15-17 (average 16.5) days.