Molting Season and Reproductive Cycle of the Japanese Crayfish, Cambaroides japonicus in a Stream and a Small Lake in Hokkaido

Abstract

The molting season and reproductive cycle of the Japanese crayfish, Cambaroides japonicus (De Haan, 1841), in a stream and a small lake in Hokkaido, were investigated once a month from 1991 to 1992. In the warm season from Jun. to Oct., molting occurred in both habitats. The size of the smallest reproductive female was 18mm in carapace length for both habitats. The reproductive cycle of this species was as follows. Mature females copulate in Sep. and Oct., and the cement gland develops from Sep. to Nov. In Apr. or May of following year, the females spawn. They lay eggs and carry hatched juveniles for two to three months, with juveniles being released in Jul. or Aug. The smallest size of mature females was equal at both habitats. Furthermore, the reproduction and molting occurred simultaneously at both habitats.