• Journal of Aquaculture
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• v.11 no.2
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• pp.141-149
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• 1998

Spawning inducement of striped knife-jaw, Oplegnathus fasciathus, was attempted by two experiments. In experiment I (Exp. I), water temperature was gradually increased from 14.5$^{\circ}C$ in December 15, 1996 to $21.0^{\circ}C.$ in February 22, `997 and then maintained at this level. Photo-period was also gradually increased from 10.5L/13.5D in December 15, 1996 to 15.5L/8.5D in February 17, 1997, and then maintained at this level. In experiment II (Exp. II), water temperature was increased in the same way from Exp. I. Photoperiod was natural conditions from December 1996 to March 9, 1997, and then suddenly increased to 15.5L/8.5D until the end of experimental period. Spawning of the fish was occurred from February 22 through April 2, 1997 (for 40 days) in Exp. I. Number of total spawned eggs was 30.04 million and fertilization rate was 77.2%. The fish began to spawn at $21.0^{\circ}C.$ and 15.5L/8.5D. It requied 65 days to spawn since the water temperature had increased from $14.5^{\circ}C.$ to $21.0^{\circ}C.$. Spawning of the fish was not occurred until March 9, 1997 in Exp. II. After 7 days, photo-period was suddenly incresed to 15.5L/8.5D and fish were spawned from March 17 through April 4, 1997 (for 20 days). Number of total spawned eggs was 21.28 million and fertilization rate was 72.1%. The fish began to spawn at $21.0^{\circ}C$ and 15.5L/8.5D. It required 65 days to spawning since the water temperature had increased from $14.5^{\circ}C$ to $21.0^{\circ}C$.

• Korean Journal of Ichthyology
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• v.12 no.1
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• pp.46-53
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• 2000

Artificial gonadal maturation and spawning inducement of striped knife-jaw Oplegnathus fasciatus were studied. Effects of water temperature and photoperiod under different regims on gonadal activity and maturation of three years old O. fasciatus were investigated histologically. In experiment I (Exp. I), water temperature was gradually increased from $14.5^{\circ}C$ to $21.0^{\circ}C$ and photoperiod was also gradually increased from 10 : 30 L to 15 : 30 L from December 1996 to February 1997 and this conditions were maintained till April. In experiment II (Exp. II), water temperature was increased in the same way from Exp. I and photoperiod was controlled as natural condition till early March and then increased to 15 : 30 L immediately. Control fish were reared in net-cage culture system in the sea from December 1996 to April 1997. Gonadal activity was initiated by increasing water temperature in both Exp. I and II from January. In Exp. I, gonadal maturation and spawning were induced from February when water temperature and photoperiod reached at $21.0^{\circ}C$ and 15 : 30 L, respectively. In Exp. II, complete gonadal maturation was not induced until early March but after treated by compensatory long photoperiod (15 : 30 L), the gonad was matured and subsequently spawning occurred.