• Korean Journal of Fisheries and Aquatic Sciences
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• v.25 no.5
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• pp.413-431
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• 1992

Gonadal development, fertilization and egg development in the maternal body and reproductive cycle of ovoviviparous rockfish, Sebastes inermis, were investigated histologically. Gonadosomatic index(GSI) of male and female were increased from September and reached maximum values in December. In the male, GSI decreased from January, but in the female maintained high values till February and decreased from March. Hepatosomatic index(HSI) was related to GSI conversely. In both sex, HSI increased from February and reached maximum in August as the gonad were degenerating and resting, and began to decrease from September as gonad were glowing. This ovoviviparous rockfish copulates in December. Fertilization with sperms maintained between ovulated oocytes in the ovary occurs in January mainly. Egg development in the ovarian cavity and discharging of hatched preiarva occurs from January to February. The reproductive cycle includes the successive stages: Growing(September), Mature (October-November), Ripe and Fertilization(Decembr-Janua), Egg development and Discharging of hatched larva(January-February), Degeneration and Resting(February-August). According to the frequency distribution of egg diameter and histological observation, the ovoviviparous rockfish discharged the prelarva at a time in a spawning season. The sexual maturation is first attained at 2 ages. All females and males reaches first maturity at body length of 17.1cm and 15.1cm respectively. The mean number of the embryos increased with the increase of the total length of female.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.3
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• pp.253-261
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• 1985

The reproduction of marbled sole Limanda yokohamae, caught near around the southeastern coast of Korea, from December 1983 to November 1984, was investigated based on such annual variations as gonadosomatic index(GSL), gametogenesis, reproductive cycle, spawning number, hepatosomatic index (HSI), and fatness. GSI began to increase in the autumn season with the onset of shorter day length and colder water temperature, and reached the maximum value in December with the shortest day length and the lowest temperature over the year. The gonad activated the proliferation of oogonia and spermatogonia in June, reached the mature stage in October, ripe in December, and spawning from the end of December to January. After spawning, it showed the resting stage which gonad remained regressive and suppressive from February to May. In addition, the adult individuals observed discharged eggs only once during their spawning period. At yolk globular stage, the substance of vitellogenin synthesized from the liver was considered to participate in the active yolk accumulation of oocytes. Marbled sole was concluded to be a typical winter spawning species in that such environmental factors as short day length and low water temperature were closely related with the gametogenesis, the stimulation of oocyte maturation, and were also affecting the ovulation.

• Journal of Aquaculture
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• v.9 no.1
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• pp.73-81
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• 1996

This study was conducted to study the reproductive cycle in female fusilier, Caesio diagramma by using the histological methods. Histological changes of the ovary were well correlated with the patterns of gonadosomatic index (GSI) and hepatosomatic index (HSI). GSI was increased in April as the value of HSI increase and reached to its maximum in May and June. Oocytes at the chromatin-nucleolus and peri-nucleolus stages were observed in the ovary throughout the year. In April, oocytes containing yolk appeared in ovaries of a few fishes. Most oocytes appearing in May and June belonged to the tertiary yolk stage. Frequency of oocytes appearance at the tertiary yolk stage in May and June was higher than that of the other months. Moreover, the empty follicles and atretic oocytes were observed in the ovaries with many vitellogenic oocytes during these two months. Thereafter, oocytes of the yolk stage disappeared in September. The spawning period of C. diagramma is from the month of April to June, and this species belongs to an asynchronous and multiple spawner.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.5
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• pp.309-315
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• 2005

Changes of sex steroid hormones in the plasma of yellowfin goby, Acanthogobius flavimanus were investigated in relation to the gonadosomatic index (GSI), the hepatosomatic index (HSI) and gonadal development. The GSI in females rose rapidly in November and remained high from December to May $(7.26\pm0.89­6.62\pm0.02)$. The Male's GSI also increased gradually from November and was highest in May $(0.16\pm0.08)$. The HSI in both sexes was in reverse correlation with the GSI, and the HSI was low during the spawning season (February-May). In females, the $estradiol-17{\beta}\;(E_2)$ level increased during vitellogenesis (November and December) and reached its maximum $(8.13\pm2.87 ng/mL)$ at the maturing period, in January. $17{\alpha},\;20{\beta}$-dihydroxy-4-pregnen-3-one$(17{\alpha}20{\beta}OHP)$ gradually increased from October $(0.063{\pm}0.02ng/mL)$ to March $(0.16{\pm}0.02ng/mL)$ and increased rapidly in May. The level of testosterone (T) showed a similar tendency of $E_2$. In males, T increased gradually during spermatogenesis from September to December $(0.14{\pm}0.06­0.26{\pm}0.10ng/mL)$ and peaked in January $(0.36{\pm}0.29 ng/mL)$ when the spermatozoa filled the testis. 11-KT also rose markedly in January and then decreased. On the other hand, $17{\alpha}29{\beta}OHP$ in males did not show any clear tendencies.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.5
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• pp.823-833
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• 1997

To clarify the annual reproductive cycle of the banded catfish, Pseudobagrus fulvidraco (Richardson), the seasonal changes in histological aspect of gonad and liver were examined. The adult fish was raptured from the upper stream of Young-San river, Chunnam in each month from May 1992 to June 1993. Based on the annual changes in GSI (gonadosomatic index), HSI (hepatosomatic index), CF (condition factor) and histological aspects of the gonads, the annual reproductive cycle were classified into 5 periods as follows: 1) Growing phase (from April to early May): The value of GSI increased and the size of oocytes in perinucleolus stage in oocytes increased gradually. Spermatogonia were developed actively from the epithelial tissues of seminiferous tubules. 2) Maturing phase (from Hay to early June): GSI levels increased rapidly in both sex. Oocytes at various developmental stages were observed. Appearance of active spermatogenesis were observed. 3) Mature and spawning phase (from June to August): High values of GSI remained static and oocytes accumulated significant quantitis of yolk globules. 4) Degenerating phase (from September to November): GSI levels decreased and ovaries were filled mostly with oocytes at the perinucleolus stage. Hepatic cells accumulated significant amounts of lipid droplets. 5) Resting period (from December to March) : Low values of GSI were kept and the size of oocytes at the perinucleolus stage did not increase. Spermatogenesis was not observed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.2
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• pp.100-106
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• 2003

This study was conducted to investigate the supplementary effects of vitamin C and E to moist pellet on growth and body composition in juvenile olive flounder (Paralichthys olivaceus). Four groups of diet made : moist pellet (MP) diet group was used as the control group where the ratio of raw feed and commercial compound meal is 5:5 $(CP\;30\%,\;CL\;17\%),$ vitamin C added group (VC), vitamin I added group (VE) and vitamin C and I added group (VCE). The supplementary amount of vitamin C and E corresponded to 1000 mg/kg (dry wt.) and 220mg/kg (dry wt.), respectively. Vitamin C was destroyed $50\%$ and vitamin E was destroyed $20\%$ for manufacturing process. After 8 weeks feeding trial, weight gain was $121.9\%$ in MP group, while it ranged from 180.5 to $184.9\%$ in the VC, VE and VCE group. Feed efficiency was $71.\6%$ in MP group, whereas it ranged from 78.7 to $80.6\%$ in the VC, VE and VCE group, weight gain and feed efficiency of fish fed vitamin supplemented diets were significantly higher than control group and no significant difference among the vitamin added groups was observed (p>0.05). There were no significant differences in moisture, crude protein, crude lipid, crude ash, condition factor (CF), hepatosomatic index (HSI), and visceraweight index (VWI) of body composition. Hemoglobin (Hb) was $3.79\%$ in MP group, whereas $4.99\%$ in VC group, $4.55\%$ in VE group and $5.07\%$ in VCE group; Hb was significantly higher in the vitamin added groups than the control group (p<0.05). Vitamin C retention in liver was 18.1, 20.7, 46.6, 54.0 mg/kg in MP, VE, VC and VCE groups, respectively. Vitamin E retention in liver was 25.9, 53.8, 88.2, 124.5 mg/kg in MP, VC, VE and VCE groups, respectively. These results indicate that supplementation of vitamin C and E to moist pellet diet significantly improved growth and feed efficiency of olive flounder, and the mixed addition of vitamin C (1,000 mg/kg dry wt.) and vitamin E (220 mg/kg dry wt.) did not lead to the synergy effect.

• Korean Journal of Environmental Biology
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• v.26 no.2
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• pp.87-93
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• 2008

To assess effects of contaminants on fish in Nakdong river, feral yellowfin goby Acanthogobius flavimanus were caugt in two different sites and its hepatic monooxygenase enzyme, including cytochrome P450 (CYP), NADPH-cytochrome P450 reductase (P450R), NADH-cytochrome b5 reductase (b5R), ethoxyresorufin deethylase (EROD), glutathione S-transferase (GST) were quantitatively determined. Gonadosomatic index (GSI), hepatosomatic index (HSI) and three sex steroid hormone (17$\beta$-estradiol, E2; testosterone, T; 11-ketotestosterone, 11-KT) levels of the fish were also investigated. HSI of fish from polluted site (site 1) were significantly higher than that of unpolluted site (site 2), but GSI levels were significantly lower in polluted site. No significant differences in plasma 11-KT and T levels were observed in two sites surveyed. E2 level was, however, significantly (p<0.05) higher in female fish from site 1 than site 2. In addition, hepatic EROD activity and CYP level of site 1 fish were lower than those of site 2 fish, whereas relatively high levels of P450R, b5R and GST activities were found in site 1. The results imply that yellowfin goby, especially female fish in Nakdong river estuary are affected from contaminants disrupting sex steroid hormone system.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.5
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• pp.713-720
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• 1998

Experiments on the control of rockfish, Sebastes inermis reproduction were performed by artificially changed water temperature (WT) and photoperiod (PP). The experiments were divided into three conditions; artificial changes of both WT and PP delayed two months against their natural variations (Exp.I), natural WT and PP replaced with artificial light (Exp.II) and natural WT and PP (Exp.III) from September to April (220 days). Initial gonadosomatic index (GSI) in female groups of experiments was 0.2. Female GSI of responded group in Exp.I began to increase from December and reached the highest value in February with 15.0, while the un-responded group kept the lower value during the experimental period. Female GSI of Exp.II and Exp.III reached the highest values in January with 13.0 and 14.7, respectively. Male GSI of Exp,I reached the maximum in October, and that of Exp.II and III reached the maximum in November and then rapidly decreased. Among the experimental groups, male GSI did not show the different tendency. Monthly changes of hepatosomatic index in both sexes showed the reciprocal tendency with those of GSI. The control of WT and PP did not affect on the changes of HSI and condition factor of rockfish. From the histological observations, maturation of ovary was delayed by the changes of WT and PP, but that of testis was not influenced. Judging from the above results, the maturation and parturition of female rockfish could be delayed one or two months by artificial changes of WT and PP.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.2
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• pp.141-148
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• 2011

This feeding experiment was conducted to investigate the effects of dietary inclusion of various additives on growth performance, hematological parameters, fatty acid composition, gene expression and histopathological changes in juvenile olive flounder (Paralichthys olivaceus). Eleven isonitrogenous (49% crude protein) and isolipidic (10% crude lipid) experimental diets were formulated: no additives (Con); 5% kelp meal (Ke); 10% krill meal (Kr); 1% garlic powder (Ga); 1% citrus meal (Ci); 3% onion powder (On); 1% ginger powder (Gi); 1% mugwort powder (Mu); 1% licorice powder (Li); 1% wasabi powder (Wa); and a mixture (Mix) of these additives. Three replicate groups of juvenile flounder (average weight of 8.5 g) were fed one of the experimental diets to visual satiety twice a day for 15 weeks. The dietary inclusion of additives did not affect survival, weight gain, specific growth rate feed efficiency, daily feed intake, daily protein intake, protein efficiency ratio, hepatosomatic index and visceralsomatic index of the fish. Plasma triglyceride levels were significantly lower in fish fed the Ke, Ga, On, Gi, Mu, Li, and Mix diets than in fish fed the control diet. Plasma glucose, glutamic oxaloacetic transaminase and total cholesterol did not differ among dietary treatments. No significant difference was observed in fatty acid composition and lipid content of the dorsal muscle in fish fed the experimental diets. Myosin gene expression did not differ significantly among treatments after 5 weeks but was significantly lower in fish fed the Kr, Ci, Li, and Mix diets than in control group after 15 weeks. Histopathological analysis showed mild gill hyperplasia and mild necrosis of liver parenchymal cells in several individuals of each experimental group. These conditions were also observed in the control group and were not thought to be related to the inclusion of feed additives. The present findings indicate that the dietary inclusion of additives did not affect growth performance, fatty acid composition, gene expression, and histopathological changes in juvenile flounder. However, plasma triglyceride content may be reduced by supplementation with 5% kelp meal, 3% onion powder, 1% garlic powder, 1% ginger powder, 1% mugwort powder, and the additive mixture.

• Fisheries and Aquatic Sciences
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• v.13 no.1
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• pp.63-70
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• 2010

Two feeding experiments were conducted to investigate the effects of dietary genetically modified (GM) soya and com on growth performance, feed utilization and body composition of juvenile olive flounder, Paralichthys olivaceus and rockfish, Sebastes schlegelii. For each fish species, four isonitrogenous (50% crude protein) and isocaloric (4.1 kcal/g) diets (designated as nGM soya, GM soya, nGM com and GM com) were formulated to contain 20% non-GM (nGM) and GM soya and com. Thirty olive flounder (initial body weight, 15.4${\pm}$0.4 g) and fifty rockfish (initial body weight, 3.1${\pm}$0.02 g) were distributed in each 400 L tank (200 L water) in a flow through system. Each experimental diet was fed to triplicate groups of fish to visual satiation, twice a day (9:00 hand 17:00 h) for 6 weeks. Growth performance was measured every three weeks. No effects of GM feedstuffs on survival were observed. Dietary inclusion of GM feedstuffs did not affect growth performance and feed utilization of fishes, except for rockfish fed GM com. Rockfish fed the GM com diet showed higher weight gain, daily feed intake and daily protein intake than did fish fed the nGM com diet, but no significant differences were observed in final body weight between the dietary treatments. Condition factor, hepatosomatic index, visceral somatic index and body composition were not altered by the inclusion of GM feedstuffs. These results indicate that dietary inclusion of GM soya and com could have no effects on growth performance and feed utilization of juvenile flounder and rockfish. Lower weight gain and feed intake in flounder and rockfish fed the diets containing 20% soya were likely due to anti-nutritional factors, rather than transgenic factors in the feedstuffs. Dietary inclusion of GM soya and com at the level tested did not alter the body composition of fishes. Further studies to investigate the effects of GM feedstuffs on health conditions and the development of fishes, as well as those of residue of transgenic fragments in ambient environments and in animals are necessary for safe use of the ingredients in aquaculture.