It is essential that Japan more strictly regulate the importation of animals and plants from other countries in order to prevent further damage to its natural environment. "Alien species" are often transported to Japan as pets sold on the international market, as parasites on food products brought home by travelers, and so on.
One well-known case in Japan was the illegal introduction of North American black bass into lakes and rivers in several areas due to the popularity of bass fishing here. This led to a drastic decline in the numbers of native bass in those habitats, as black bass are predatory. Currently, there is a similar problem with North American raccoons brought to Japan as pets. When many owners witnessed the raccoons' fierce behavior and realized how unsuitable they were as pets, they released the animals into the wild, where they now spread disease such as rabies and damage crops.
In 1920, hunting enthusiasts released 100,000 Korean pheasants, which resulted in a mixed breed of pheasant. The release of the Korean pheasant continues, and bird specialists claim that native Japanese pheasant are now extinct. Add to these invasions the encroachment of Chinese bamboo in rural areas, and Japan ends up with damage to the habitat and life cycle of native plants and animals and, ultimately, the extinction of those species.