The Toxicity of Digestive Gland of Trumpet Shells Inhabiting the Coast of Shizuoka Prefecture

Abstract

A total of 691 specimens of a trumpet shell Charonia sauliae were collected from several locations in Shizuoka Prefecture, and assayed for toxicity of the digestive gland by the official method for tetrodotoxin determination.1) The frequency of toxic specimens ranged from 30% at Ito to 93% at Shimizu, the average frequency being 66%.2) The average toxicity of all the specimens assayed was 151MU/g digestive gland. The toxicity score was clearly higher at Shimizu (226MU/g) or Numazu (277MU/g) than at other places.3) The highest toxicity scores recorded at Shimizu and Numazu were 1, 950 and 2, 580MU/g digestive gland, respectively. At other places, however, fairly toxic specimens (400-500MU/g digestive gland) were found sporadically.4) The toxicity of trumpet shells in the Shimizu area has tended to decrease in recent years.5) At Numazu, the toxicity of trumpet shells was higher in spring and summer than in other seasons. Shimizu specimens did not show such a seasonal variation.