Studies on the Artificial Propagation of the Large Yellow Croake, Pseudosciaena crocea (Richardson)
Lin Danjun Zhan Jian(The Research Laboratory of Developmental Biology, Department of Biology) Zheng Zhiying Weng Zhongchai Shu Yaozhang (Mingdong Fisheries Institute, Linde)
The experiment of this study had been carried out in 1989 and 1990. The parent fishes were artificially cultured in the floating net cages on the sea over three years. They were moved into indoor sponds in Decemder, and kept in fit temperature (16℃) with favorable feeding and injected small dosage of LRH-A every 15—20 days for 3—4 times. The method seemed to be very effective on promoting the gonadal development and increasing the mature rate of the parents, especially for fishes of 3—4 years old.There were two breeding seasons for the Large Yellow Croake in a year. Most of the fishes were induced to spawn from middle April to early June. During the oestrus, the males and the females both gave a "Go—Go—Go" sound, soon the females would lay eggs in batches. The behavior would last for 2—3 days until all mature eggs were spawned. The spawning took place at about 9:00 in the evening till 3:00 next morning, 36 hours after injection of LRH-A or DOM_+ SGnRH. The eggs were naturally fertilized in the spond water, and hatched in about 35 hours under the condition of temperature 20—22℃ and salinity 18.9—22.9‰. Lower salinity (below 20.2‰) would greatly influence the development and floatability of the eggs.