Abstract
Various types of episodic decrease or disappearance of seaweed bed, resulting in the formation of barren
grounds (not necessarily coralline community), have been called Isoyake in Japan. Among the barrens, offshore
types are more popular than the other types (inshore, middle, whole and spotted). It should be noticed, however,
that they include stable barrens just below the lower limits of algal vegetation. Recent literatures of 'Isoyake' in
domestic and other areas in the world suggest that anthropological reasons (e.g., overfishing of predating animals,
eutrofication) as well as oceanographic natural disasters (e.g., El Nino, inshoring of Kuroshio) can induce barrens.
Therefore, the targets of 'Isoyake' research should be placed on the establishment of ruled fisheries and balanced
utilization of coastal waters.
