Selection of Spawning Ground and Spawning Bed in Oval Squid Sepioteuthis lessoniana

Abstract

Selection of spawning ground and spawning bed in oval squid, Sepioteuthis lessoniana, was studied in use of four different types of man-made spawning beds settled in the coastal waters of Tokushima prefecture. Under- water observations and sampling of egg capsules were carried out by SCUBA diving during a period from May 1990 to September 1993. The number of egg capsules laid on the man-made spawning bed placed in the calm waters of the inlet was much more than that in the ground facing to the open water. The number of egg capsules laid on man-mnde spawning bed was ranked by the bed type as, mid-water cage type > steel type > fiberglass reinforced plastics (FRP) type, with small difference. These three types of man-made spawning beds were recognized to be superior in respect to the mass of laid egg compared with the neighboring natural spawning beds composed of Sargassum and Zostera. The results obtained suggest that spawners prefer a calm waters, and select in relatively wide range of artificial materials for egg-laying.