2022 Volume 88 Issue 5 Pages 386-395
In order to clarify the growth of male beni-zuwai crab Chionoecetes japonicus, the mean carapace width at each instar was estimated by decomposing the polymodal size frequency distributions of male crabs collected from the central part of Toyama Bay at the depth of 1055-1270 m by beam trawls from 2006 to 2012 and by crab pots in 2004 and 2011. The mean sizes from the 3rd to 13th instar were estimated to be 6.3, 9.1, 12.9, 18.0, 25.5, 34.1, 44.6, 58.3, 74.0, 88.3, and 105.8 mm CW, respectively. The ratios of adult male crab with relatively large-sized chela were 2.8%, 11.4%, 34.9%, and 74.0% at the 10th to 13th instars, respectively, which indicated that the proportion of morphometrically mature male crabs increased greatly from the 12th to 13th instar.
