Marine afforestation of Ecklonia cava by using a net cage for protection from grazing was examined in the Hainan Isoyake area of Shizuoka Prefecture. Algal reef blocks made of concrete were placed on the bottom of a rocky reef at 12 meters deep in October 1997,onto which hundreds of E. cava plants grown in a water tank were transplanted. The E. cava plants were covered with a net cage for protection from grazing by herbivorous fishes, and the net cage could be removed in the winter, when grazing pressure by the herbivorous fish Siganus fuscescens, decreased. E. cava plants consisting of multiple-year classes survived on the algal reef blocks with a net cage in the summer of 2000, and many young plants spread over the natural rocky reefs around the algal reef blocks. The E. cava that spread around the algal reef blocks were grazed by S.fuscescens in the autumn and disappeared. However, E. cava spread again in the spring of the following year and grew in the summer.
