Hemicentrotus pulcherrimus in the Tohoku area is not utilized as a fishery product because the ovaries have a bitter taste almost all year. To discover the cause, we compared the annual reproductive cycles and ovarian accumulation of a bitter amino acid, pulcherrimine, in H. pulcherrimus collected at Mikuni (Fukui Prefecture), where it is fished in summer, and Iwaki (Fukushima Prefecture), where it is not utilized. At both sites, pulcherrimine increased in maturing ovaries as oogenesis proceeded from autumn to winter, decreased after spawning in spring, but remained in spent and immature ovaries for a few months. In Mikuni, pulcherrimine was scarcely detected in the ovaries for several months in summer. However, in Iwaki, late spawning delayed the disappearance of pulcherrimine in summer, and early initiation of oogenesis advanced the restart of pulcherrimine accumulation in autumn compared to Mikuni. Consequently, the period when the ovaries were palatable because of the absence of pulcherrimine during summer was short in Iwaki. The major cause of such short-term palatability could be the lower seawater temperature in the Tohoku area. Furthermore, pulcherrimine was never detected in other sea urchins, although a bitter taste was found in the mature ovaries of some species.

由于东北地区的卵巢几乎一年四季都充满苦味，因此东北地区的半球形半绒藻不被用作渔业产品。为了发现原因，我们比较了H. pulcherrimus中苦味氨基酸pulcherrimine的年度繁殖周期和卵巢积累。在夏季捕鱼的三国（福井县）和未利用的岩城（福岛县）收集。在这两个地方，随着卵子的生成从秋天到冬天，成熟时卵巢中的Pulcherrimine增加，在春季产卵后减少，但在乏用和未成熟的卵巢中保留了几个月。在三国，夏季几乎没有在卵巢中检测到Pulcherrimine。但是，在磐城，晚产卵推迟了夏天夏草碱的消失，与三国相比，早产卵的发生促进了秋天夏草碱的重新开始。因此，岩城县由于夏季缺乏长春碱而卵巢可口的时期很短。这种短期适口性的主要原因可能是东北地区海水温度降低。此外，尽管在某些物种的成熟卵巢中发现了苦味，但从未在其他海胆中发现过普尔可利明。