Study on larval early development and point of no return of hybrid F₂ of Acanthopagrus schiegelii (♀)×Pagrus major (♂)

With the hybrid F₁ Acanthopagrus schiegelii (♀) ×Pagrus major (♂) as parents, we analyzed the early development and point of no return (PNR) of hybrid F₂ which were naturally fertilized and artificially incubated at the water temperature of (21.8±0.4) ℃ in April, 2017. The results show that the total length of the newly hatched larva was (2.40±0.15) mm, and the larva started feeding at 3 dah with the mixed feeding stage lasting 4−5 d. The yolk sac disappeared at 7 dah and the total length was (3.95±0.04) mm. The initial feeding rate and the highest feeding rate were 45.80% and 77.21%, respectively. The initial feeding rate dropped significantly to 29.83% at 6 dah and the PNR appeared. In the starvation group, the larvae experienced negative growth and had significant difference at 5 dah (P<0.05) and very significant difference at 5 dah (P<0.01) in the total length with the control group. It is indicated that the development of hybrid F₂ larvae was good, and the optimum initial feeding time for the larvae was within 3 d after their mouths opened.