The tolerance to and optimal salinity for growth in swimming crab Portunus trituberculatus “Huangxuan No.1”

The tolerance of swimming crab Portunus trituberculatus Huangxuan No.1 to salinity was studied in a laboratory.The results showed that the swimming crab had salinity LD50 of 5.13 for 24 h,7.49 for 48 h,and 8.56 for 72 h,though it was safely alive in salinity from 13.7 to 47.7.The 80-day old swimming crab juveniles were reared at a safe salinity of 18.7,23.7,28.7,33.7(control),38.7,and 43.7 for 40 days.It was found that the juveniles showed a survival rate of 60% at a salinity of 18.7,59% at 23.7,63% at 28.7,49% at 33.7,48% at 38.7,and 38% at 43.7.There were significantly higher survival rate,weight gain rate and molting frequency in the swimming crab at lower salinity of 18.7,23.7 and 28.7 than those in the other groups at higher salinity of 33.7,38.7,and 43.7.Comprehensive comparison suggests 28.7 be the optimal salinity for growth in Huangxuan No.1.