Advanced spawning of yellowtail Seriola quinqueradiata as early as December by manipulations of both photoperiod and water temperature
2006
Hamada, K.(National Center for Stock Enhancement, Goto, Nagasaki (Japan). Goto Station) | Mushiake, K.
The present study examined the combined effects of photoperiod and temperature control on the ovarian maturation and human chorionic gonadotropin (HCG)-induced spawning of yellowtail Seriola quinqueradiata, with the aim of achieving advanced spawning as early as December. In experiments conducted from 2002 to 2004, the daylength was set to 8 hours (8L16D) for 10 days followed by a 10-hour daylength extension to 18 hours (18L6D) for the next 80 days under controlled water temperature that was maintained at 19 deg C before the injection of HCG. Female broodstock kept under these controlled conditions were induced to mature more rapidly than those kept under natural conditions. Neither controlled photoperiod nor controlled water temperature was sufficient to induce the maturation of fish. During these 3 years, fish kept under both controlled conditions were able to spawn in advance during December, with the total eggs produced per female ranging from 87 X 10(3) to 1000 X 10(3). Survival rates for the first 10 days of the rearing experiments of larvae at first spawning obtained in 2002 and 2004 were 14.1 and 36.7%, respectively. These values were similar to those obtained during the spawning season in April. This experiment showed that manipulations of both photoperiod and water temperature are effective in accelerating the maturation of female yellowtail broodstock and that good quality eggs may be obtained as early as December after HCG injection.
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