Abstract: In order to find out how hydration would affect hatching of Artemia salina cysts at early stages in Bohai Bay, an experiment had been designed in which different water temperatures and different action times were involved. In the experiment, there were five different temperatures which were 20 ℃, 25 ℃, 30 ℃, 35 ℃ and 40 ℃, and each with five different action times which were 1 hour, 2 hours, 3 hours, 4 hours and 5 hours. The experiment result showed that hydration had an obvious impact on hatching of Artemia cysts. Under temperature of 30 ℃, hydration could help shorten hatching process. Time of umbrella-shaped period and time of Artemia larvae stage were both advanced at different experimental times and temperatures except for temperature of 40 ℃, so did time of 5% and 95% hatching completeness. The result also indicated that as temperature gone up above 35 ℃ gradually, this effect started to reduce. In addition, hydrating temperature and time had a significant effect on hatching when water temperature was between 25℃ and 35 ℃. In this temperature range, the higher temperature was, the higher the hatching rate was. Longer-hour experiments like 4-hour and 5-hour were the most significant compared with the control group. Yet opposite result was observed at temperature of 40 ℃ at all times. Base on this, hydrating condition of 25 ℃ with the action time of 3 hours was considered to be the most beneficial for hatching Artemia cysts in Bohai Bay. Under this experimental condition, the hatching rate reached up to（86.41±0.03）%, which was（6.84±0.04）% higher than that of the control group and the hatching time of completing most of the incubation was reduced by 2 hours.

Key words: Artemia salina, hatch, water temperature, time, hydration