Protecting Lake Akan’s Marimo

Lake Akan in eastern Hokkaido is home to the world's only population of large, spherical marimo algae. Once found at four sites in the lake, they now grow in just two northern bays: Churui and Kinetanpe. The species was declared protected in 1921 after decades of theft, and was classified critically endangered in 1997. Development of Akanko Onsen town around 1960 caused eutrophication that threatened the marimo, leading residents to clean the lake and build sewage treatment facilities. Every October the Marimo Festival ceremoniously returns any marimo raised in captivity back to the lake.