Seasonal changes of bitterness and pulcherrimine content in gonads of green sea urchin Hemicentrotus pulcherrimus at Iwaki in Fukushima Prefecture

Abstract

The tri-monthly changes in the gonad index (GI), the frequency of bitter gonads, and the contents of a novel bitter amino acid, pulcherrimine of green sea urchin Hemicentrotus pulcherrimus caught off Iwaki, are described. The mean GI values of mature male and female individuals were lowest in May 1999. Immature individuals were found in May, August, and November 1999, and their percentages were 20%, 60%, and 4%, respectively. However, many mature sea urchins were found in all the months examined. More than 95% of mature ovaries had a bitter taste in November 1998, February 1999, and November 1999; whereas in May and August 1999, only 60% of the mature ovaries had a bitter taste. In August 1999, 20% of the immature gonads tasted bitter. Individuals with a low pulcherrimine content in their ovaries increased from February to August 1999 and decreased from August to November 1999. These results suggest that the amount of pulcherrimine in the ovaries of the green sea urchin is related to seasonal changes.