ズワイガニの初産卵期における分布状況

抄録

In order to examine the distribution patterns during the primary spawning period of the snow crab Chionoecetes opilio, sampling surveys were carried out by means of crab traps from depths between 236m to 250m in the sea off Kyoto Prefecture in October 1986 and 1988, and July 1990
Two groups of female crabs, which were categorized as primiparous females just before and after the first mating and multiparous ones more than a year after mating, tended to form patchy aggregations, mostly separated by the bathymetric boundary of 243m depth. That is, the former was distributed in a shallower area than 243m and the latter in a deeper one. These distribution patterns followed two patchy aggregations of males: one a with small carapace for the primiparous females and the other with a large carapace for multiparous fe-males, respectively.
In mating during the primary spawning period from July to October, the distribution pat-tern of primiparous females concurred with the large scale patchiness of males in non-terminal molt with small carapace size. It is suggested that small males can mate with primiparous females in areas shallower than around 250m.