Toyama Prefectural Fisheries Research Institute, Namerikawa, Toyama 936-8536, Japan
Red snow crab Chionoecetes japonicus were collected from the central part of Toyama Bay at the depth of about 1,000-1,250 m by a beam trawl in summer and winter from 2000 to 2006, in order to investigate their growth in the juvenile stage. Carapace width (CW) measurement revealed six modes of size-frequency distribution in the range of 5-40 mm CW in both males and females. Dividing into the six normal distributions, the mean size in CW in each one was estimated to be 6.4, 9.2, 13.3, 18.0, 25.4 and 33.7 mm in males, and 6.5, 9.0, 12.7, 17.9, 24.3 and 32.6 mm in females, which were thought to mean CW at the 3rd to 8th instars, respectively. There was a tendency for crabs in the 4th and 6th instars to occur dominantly in summer and in the 5th instar to do so in winter.