Abstract
Barren ground, so-called Isoyake in Japanese, exists along the southwest coasts of Hokkaido, Japan. In the
Isoyake area, the sea urchin, Storongylocentrotus nudus, dominates the bed rock, and occurrence of the kelp,
Laminaria religiosa, was limited in the refuge at shallower zones. To develop the kelp forest technology in the
Isoyake area, seasonal changes of some environmental factors, water movement, water temperature, vegetation,
and grazers, were observed continuously during 1998 to 1999 in Oshoro Bay. Environments conducive to kelp
forest were characterized ; sea urchins took refuge from strong water movement in deeper zones and.kelp buds
were prptected from overgrazing during winter. We propose two methods to increase the kelp forest in Isoyake
area : 1) seasonal control of excess grazing pressure using fences and, 2) adjustment of the depth with block and
stone to remove urchins by increasing wave velocity.
