With an ever-increasing number of foreign aquatic species threatening ecosystems in many areas of Japan, municipalities are calling on people not to release them into the local environment.
Most of the foreign species, such as bluegill and red-eared slider, are believed to have been released in ponds and other places by former owners. Local residents are attempting to eradicate them by means of "kaibori," a traditional agricultural practice of draining ponds.
Japanese farmers used to conduct kaibori during agricultural off-seasons to prevent irrigation ponds from being silted up by mud. In recent years, kaibori has often been used for the purpose of environmental conservation as it is considered a practical way to catch foreign species.