Restoration of Kelp Beds on an Urchin Barren: Removal of Sea Urchins by Citizen Divers in Southwestern Hokkaido

Watanuki, A., T. Aota, E. Otsuka, T. Kawai, Y. Iwahashi, H. Kuwahara and D. Fujita

Publication Date:

As the fishermen on the coast are aged and depopulated, the authors introduced citizen volunteer divers (CVD) for the removal of the sea urchin. The attempt was practiced on an urchin barren near Kamoenai Fishing Port on the southern coast of Shakotan Peninsula in September 2005. Twenty CVD (including a few instructors and staffs) removed sea urchins from two blocks (50 x 50 m, 4-8m in depth) during two dives (ca. 1 hr/dive) beside the control block; subsequent monthly removal by monitors (i.e., researchers) was done in one of the two blocks. In May 2006, the average standing crops of the seaweed (largely kelp) were 865g/m2 (monthly removed after the CVD activity) and 150g/m2 (removed once by CVD) but 0g/m2 in control, while the density of sea urchin were 0.1, 3.5 and 4.2/m2, respectively. The results show that the introduction of CVD can aid the restoration of kelp beds.

Resource Type:
Peer-reviewed Article

Bulletin of Fisheries Research Agency