100 most damaging foreign species identified

The Ecological Society of Japan has compiled a list of 2,200 foreign species in a new handbook, identifying 100 as the “most aggressive” for the damage they have wrought on Japan’s indigenous flora and fauna.

Among the foreign species on the “worst 100” list are black bass (Micropterus salmoides) and bluegill sunfish (Lepomis macrochirus), both introduced in Japanese rivers and lakes for sports fishing.

The common raccoon (Procyon lotor) was in the worst marauding mammals category. The species is infamous for the damage it causes to farmers’ crops in Hokkaido and other regions of northern Japan.

A popular pet, American crawfish, was described as “the world’s most infamous crawfish.” Known by its scientific name Cambarus clarkii, this bright red creature eats small aquatic animals and water plants.

The handbook warns of the hybridization of the common dandelion (Taraxacus officinale weber) with indigenous species, as well as the damage to plants caused by the Mexican bean beetle (Epilachna varivestis).

The ecological impact of foreign species has also attracted the attention of the Environment Ministry, which has created a database and printed brochures to raise public awareness.

Izumi Washitani, a professor at the University of Tokyo who supervised the editing of the Ecological Society’s foreign species handbook, said he hopes the book serves as a wake-up call to people who want to import animals that are alien to Japan’s ecology.

“I want people to know how the once rich Japanese habitat has been ravaged by foreign species,” he said.

Washitani urged pet owners to look after their pets and make sure they are not released into the wild.

The handbook, priced at 4,000 yen, is published by Chijin Shokan.