アコヤガイ増殖に関する研究-I

Abstract

In the present paper, the writer reports the data obtained from the experiments collecting planetonic larvae and young spats of the pearl oyster, Pinetada martensii. which were carried out, during June, July, August and September of 1951, at the Nasa Bay near Shishikui-machi, Tokushima Prefecture. The results of these experiments are summarized as follow: (1) The natural production of the pearl oyster are closely affected by the conditions of environment during July. (2) It is assumed that about 25 days are necessary for the D-shaped veliger to develop to the so-called full grown stage. In this year, the largest collection of the veliger larvae was occurred on July 20 th, and the largest one of the full-grown larvae on August 13th. (3) The young spats settled on collecters of these experiments are induced to belong to the same population by the statistical measurement on the destribution of shell length. (4) No spat settles on the fresh collecter. On the other hand, the settled spats are found abundantly, after the collecter becomes dirty to some extent. It is supposed that 16-18 days are necessary for the collecter to become dirty in a suitable degree. (5) It is concluded, therefore, that the optimum season for setting collecter seems to be about the middle of July and the maximum settlement of the spats to be about the middle of August.