Abstract
Individual density and reproduction of Cambaroides japonicus in a stream, the southernmost habitat of this species, Oodate City, Akita Prefecture, were studied from 1981 to 1989. Decrease of the animal density was caused by shallow depth indicating water volume of the habitat. The relationship between carapace length (X, mm) and number of eggs attached to pleopods (Y) was Y=-50.69+4.704X. In the stream, spawning season is March and April. Hatching is caused in June and July. An adult female spawns one time in a year.
