1Shibushi Laboratory, National Research Institute of Aquaculture, Fisheries Research Agency, Shibushi, Kagoshima 899-7101, 2Department of Marine Biosciences, Faculty of Marine Science, Tokyo University of Marine Science and Technology, Minato, Tokyo 108-8477, 3Tamano Laboratory, National Research Institute of Fisheries and Environment of Inland Sea, Fisheries Research Agency, Tamano, Okayama 706-0002, Japan
To determine the optimal rearing salinity for the larval horsehair crab Erimacrus isenbeckii, newly hatched larvae were reared in groups of 50 in 2-L beakers, the salinity level of which was regulated at 10 to 45 psu (5 psu interval). Survival rates of larvae were high in the beakers of 30 and 35 psu. Mass mortality occurred in the beakers of 10, 15 and 45 psu from the first to fourth zoeal stage, and 20 psu at the megalopal stage. The number of days required to reach each larval stage increased at lower and higher salinity levels, and decreased at 25 psu. The coefficient of variation of the number of days required to reach the first crab stage was high at 25 psu. Carapace length tended to decrease at 40 psu. The numbers of prey eaten by larvae were high at 25 to 35 psu. We concluded that the optimal range of rearing salinity for larvae of the horsehair crab is from 30 to 35 psu.