Invasive Species in Shimane

Shimane's waterways, forests, and roadsides are under pressure from invasive species introduced to Japan from other continents over the past century and a half. Bullfrogs and nutria from the Americas have spread through local ponds, while large-mouth bass, brought to Japan for sport fishing in 1925, threaten aquatic life throughout the river system. The red-billed leiothrix, a Chinese songbird introduced during the Edo period and later escaped from captivity, now competes directly with the native Japanese bush warbler. Lanceleaf tickseed and Canada goldenrod have taken over roadsides across the prefecture. Conservation groups and volunteers regularly pull up invasive plants and drain ponds to remove bass.