Seasonal Variations of Nutritive Components and Several Nutritive Elements in Short-neck Clam, Tapes japonica

Abstract

The amounts of nutritive components and several nutritive elements were determined monthly throughout a year for the edible portion of short-neck clams, Tapes japonica, being caught at Aio in Yamaguchi Prefecture from April of 1977 to April of 1978. Results obtained were as follows.
The seasonal variation throughout the year in the contents of moisture, proteins, lipids, and ash is small, while that of carbohydrates is large. The coefficient of the variation in the content of carbohydrates is 51%, and the content increased from April to July when shortneck clams seemed to be in season, and decreased rapidly thereafter. The total amount of the content of carbohydrates and moisture is nearly constant throughout the year.
The patterns of the seasonal variation of Fe, Mg, and Na contents are similar to that of the ash content. The characteristics of the pattern consisted in the increase from late autumn to winter, when the growth of short-neck clams stops. The Ca content is nearly constant throughout the year. The content of P varies in the opposite direction to that of K, that is, in October the P content has a maximum value, while the K content has a minimum one.