Annual Reproductive Cycle of the Sea Urchin, Hemicenlrotus pulcherrimus in Southern Hokkaido
1992 Volume 40 Issue 4 Pages 475-478
Details
1992 Volume 40 Issue 4 Pages 475-478
Annual reproductive cycle ofHemicentrotus pulcherrimuswere examined from October, 1988 to October, 1989 in the shallow waters of Matsumae, southern Hokkaido. The gonad index increased abruptly from November and reached a maximum in December to March. Above 60 % of animals possessed mature gametes that oozed from enlarged gonads from December to May. Spawning occurred from April to June when the gonad index decreased sharply and relict gametes oozed from shrunken gonads. The spawning season in southern Hokkaido was later than that in Honshu (November-April) .
It was assumed that the delay of their spawning was attributed to low temperature in winter.
