Abstract

Plasma steroid hormone levels in the viviparous rockfish (Sebastes schlegeli) were examined in relation to gonadal histology under controlled photoperiods and water temperatures. To investigate those effects in S. schlegeli the photoperiod was maintained at 15L:9D in June and then it was gradually decreased to 9L: 15D in October. It was then gradually increased to 12L:12D in January, followed by 14L:I0D in February. The water temperature was $19-20^{\circ}C$ in July. From August to October, it was from $18^{\circ}C\;to\;12^{\circ}C$. Then, it was dropped to a low of $19-11^{\circ}C$ in November to December and then gradually increased to $14-15^{\circ}C$ in February. In females, both plasma $estradiol-l7\beta\;$ (E2) and testosterone (T) levels from August to February showed a similar pattern in both the treatment and the control groups. In the treatment group, the peaks of plasma E2 and T were observed in November, and the peaks were closely correlated to histological observations. Oocytes contained many yolk globules (final vitellogenic oocytes), and oocytes at the migratory nucleus stage increased in size. Plasma levels of progesterone did not change much throughout the experimental period. However, in the control group, the peaks of E2, T, and progesterone were observed in February. These results indicate that the controlled photoperiod and water temperature accelerated sexual maturity, corresponding to the advancement of plasma E2 and T peaks by approximately 3 months. In males, plasma T levels showed a similar pattern from August to October in the treatment and control groups, though levels in the treatment group were higher than those in the control group. From histological observations, the treatment group copulated one month earlier.

주제어

#Rockfish   #Photoperiod   #Temperature   #Steroid hormone   #Maturation  

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참고문헌 (25)

1. Aida, K., T. Kato and M. Awaji. 1984. Effects of castration on the smoltification of precocious male masu salmon Oncorhynchus masou. Bull. Jap. Soc. Sci. Fish., 50, 565-571 
2. Bae, H.C., S.C. Chung, J.J. Lee and Y.D. Lee. 1998. Annual reproductive cycle and embryonic development within the maternal body of the marbled rockfish, Sebastiscus marmoratus from the Cheju Island. J. Kor. Fish. Soc., 31, 489-499 
3. Baek, J.M., C.H. Han, D.J. Kim, C.W. Park and K. Aida. 2000. Reproductive cycle of a rockfish, Sebastes schlegeli. J. Kor. Fish. Soc., 33, 431-438 
4. Bromage, N., M. Porter and C. Randall. 2001. The environmental regulation of maturation in farmed finfish with special reference to the role of photoperiod and melatonin. Aquaculture, 197, 63-98 
5. Carrillo, M., S. Zanuy, F. Prat, R. Serrano and N. Bromage. 1993. Environmental induction of spawning in sea bass. In: Recent Advances in Aquaculture, vol. 4, Roberts, R.J. and J. Muir. eds., Blackwell, Oxford, pp. 43-54 
6. Chang, Y.J., H.K. Lim and S.G. Byun. 1995. Gonadal maturation and reproductive cycle in oblong rockfish, Sebastes oblongus. J. Aquacult, 8, 31-46 
7. Chang, Y.J., H.K. Lim and J.Y. Kwon. 2001. Changes in plasma steroid hormone level in rockfish (Sebastes inermis) by the controlled water temperature and photoperiod. J. Kor. Fish. Soc., 34, 13-16 
8. Chung, E.Y. and Y.J. Chang. 1995. Ultrastructural changes of germ cell during the gametogenesis in Korean rockfish, Sebastes schlegeli. J. Kor. Fish. Soc., 28, 736-752 
9. Hyun, C.H. and S. Rho. 1996. Studies on the early growth of rockfish, Sebastes schlegeli. J. Aquacult., 9, 25-42 
10. Kim, Y.K. and K.H. Han. 1991. The early life history of rockfish, Sebastes schlegeli. Kor. J. Ichthyol., 3, 67-83 
11. Ko, C.S., Y.J. Chang, H.K. Lim, J.H. Kim and K.C. Cho. 1998. Controlled reproductive cycle of rockfish (Sebastes inermis) by water temperature and photoperiod. J. Kor. Fish. Soc., 31, 713-720 
12. Kusakari, M. 1991. Mariculture of kurosoi, Sebastes schlegeli. Env. BioI. Fish., 30, 245-251 
13. Kusakari, M, Y. Mori and K. Kudo. 1977. Studies on the breeding habit of a rockfish, Sebastes schlegeli (Hilgendorf). 2. On the breeding behavior of pregnant fish and the just spawned larvae. J. Hokkaido Fish. Exp. St., 34, 1-11 
14. Kwon, J.Y., Y.J. Chang Y.C. Shon and K. Aida. 1999. Plasma and ovarian thyroxine levels in relation to sexual maturation and gestation in female Sebastes inermis. J. Fish BioI., 54, 370-379 
15. Lam, T.J. 1983. Environmental influences on gonadal activity in fish. In: Fish Physiology, Vol. IXB, Hoar, W.S., D.J. Randall and E.M. Donaldson, eds., Academic Press. New York, pp. 65-116 
16. Lee, T.Y. and S.Y. Kim. 1992. Reproduction and embryonic development within the maternal body of ovoviviparous teleost, Sebastes inermis. Bull. Kor. Fish. Soc., 25, 413-431 
17. Lee, Y.D., S. Rho, Y.J. Chang, H.J. Baek and C.M. An. 1996. Sex differentiation of the rockfish, Sebastes schlegeli. J. Kor. Fish. Soc., 29, 44-50 
18. Manire, C.A., L.E.L. Rasmussen, D.L. Hess and R.E. Hueter. 1995. Serum steroid hormones and the reproductive cycle of the female 'bonnethead shark, Sphyma tiburo. Gen. Compo Endocrinol., 97, 366-376 
19. Nagahama, Y, A. Takemura, K. Takano, S. Adachi and M. Kusakari. 1991. Serum steroid hormone levels in relation to the reproductive cycle of Sebastes taczanowkii and S. schlegeli, Env. BioI. Fish., 30, 31-38 
20. Park, M.E., S. Rho, S.C. Byun, C.H. Lee, H.J. Baek, Y.D. Lee and H.B. Kim. 2001. Regulation of copulation and parturition in black rockfish, Sebastes schlegeli by photoperiod and temperature. J. Kor. Aquacult. 14(3), 173-180 
21. Takahashi, H., K. Takano and A. Takemura. 1991. Reproductive cycles of Sebastes taczanowskii, compared with those of other rockfishes of the genus Sebastes. Env. Biol. Fish., 30, 23-29 
22. Takemura, A., K. Takano and H. Takahashi. 1987. Reproductive cycle of a viviparous fish, white edged rockfish, Sebastes taczanowskii. Bull. Fac. Fish. Hokkaido Univ., 38(2), 111-125 
23. Wourms, J.P., B.D. Grove and J. Lombardi. 1988. The maternal embryonic relationship in viviparous fishes. In: Fish Physiology, Vol. XIB, Hoar, W.S. and D.J. Randall. eds., Academic Press. New York, pp. 1-134 
24. Yamada, J. and M. Kusakari. 1991. Staging and the time course of embryonic development in kurosoi, Sebastes schlegeli. Env. BioI. Fish., 30, 103-110 
25. Zanuy, S., F. Prat, M. Carrillo and N. Bromage. 1995. Effects of constant photoperiod on spawning and plasma 17$\beta$oestradiol levels of sea bass (Dicentrachus labrax). Aquat. Liv. Res., 8, 147-152 

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