月齢に伴うスルメイカの生態行動

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In the waters around the Oki Islands in the Japan Sea, a common squid, Ommastrephes sloani pacificus STEENSTRUP, is plenty caught between November and February in every year. During the period the vertical and horizontal migrations of the squids are active on the moon nights, especially on the nights of the first and last quaters of the moon the migrations and copulation are accelerated, and sometimes the greater part of squids surges on the ashore. On the moonless nights the migrations are inactive, however, the feeding is active. Some fishermen catch the squids by angling off the Islands on moonless nights, the others catch them by the trap-nets in the coastal waters. The larger quantities of squids are caught by the trap-nets on the moon nights than the moonless nights. The presence of the outer tunic without the spermatophore in the stomach of female in-dividual may be considered as an evidence of copulation. The total of the squids caught by the fixed nets and the percentage occupied by the female ones in it, which have copulated, are represented on Fig. 4. Fig. 4 shows undoubtedly that the copulation of squids has a close relation with the age of the moon.
公益社団法人日本水産学会の論文