[Tolerance of Huso dauricus embryo at its different development stages to low temperature]

This paper studied the embryo hatching rate and larva survival rate of Huso dauricus when the embryo at its different development stages was exposed to low temperature for different durations. The results showed that the embryo at its yolk plug, narrow-opening, and neural block closing stages could not survive at 2 - 8 degrees C over 24 h. When exposed to 2 - 8 degrees C for 3 days, the hatching rate of embryo at its cleavage, early blastula, and mid gastrula stages was lower than 30%. Both the embryo hatching rate and the larva survival rate were higher than 70% when the embryo at its late blastula, early blastula, optic rudiment, tail bud, heart beating, and tail touching head stages was exposed to 5 - 8 degrees C for 3 days. The death rates of embryo and larva under low temperature were increased with time. There was a negative correlation between the exposure duration at low temperature and the embryo hatching rate (r = - 0.8024) and larva survival rate (r = - 0.8468) of H. dauricus. The embryo at its late blastula, early gastrula, and optic rudiment stages had a stronger tolerance at 5 degrees C for 10 h, with the embryo hatching rate and larva survival rate being higher than 70%. It could be concluded that there was a little difference in embryo hatching rate and larva survival rate of H. dauricus when the embryo at its some development stages was preserved at low temperatures at least for 10 - 15 days and at normal temperature (16 - 17 degrees C).