Studies on Tangible/Intangible Measures for Seaweed Bed Recovery

Abstract

Reduction of seaweed beds called ‘isoyake’ has happen in most of coastal prefectures in Japan, most of are due to excessive grazing by sea urchins and herbivorous fish. Several studies and countermeasures have been undertaken to recover from barren ground, but there were problems such as one-off trials and impracticality, therefore, it was necessary to show the concept and procedure of systematic measures. First, Isoyake Recovery Guideline (First Edition, Fisheries Agency, 2007) showed the basic concept and concrete procedure for countermeasures as follows. (i) adaptive management for successful reforestation through continuous learning and feedback control, (ii) flow chart consisted for selecting appropriate recovery techniques, (iii) organized cooperation of volunteers, citizens, enterprises, specialists, and local governments to support fishermen. Next, from the elemental technology development for tangible/intangible measures, reforestation facilities that control of sea urchin grazing with stones and blocks, development of sea urchin suction device and technological development to remove the gathering Kyphosua bigibbus with a gill net were briefly outlined.