Katsuki NAKAI (Lake Biwa Museum)

Largemouth bass Micropterus salmoides and bluegill Lepomis macrochirus are the most invasive among the 13 fishes selected as “Invasive Alien Species (IAS)” stipulated by the “Invasive Alien Species Act (IAS Act)”, considering the geographical distributional scale, the variability of inhabiting water bodies, and the intensity of ecological impacts. Before the enforcement of the IAS Act in 2005, the Fisheries Agency has been carrying out a series of research projects to develop effective techniques and methods to suppress these invasive fishes together with the other IAS, smallmouth bass M. dolomieu and channel catfish Ictalurus punctatus. The Ministry of the Environment also started several “model” projects for effective control of largemouth bass and bluegill in 2005. In addition to these “official” countermeasures, a variety of NPO/NGO having engaged in control of these fishes for recovering biodiversity, reviving fisheries, and reducing social conflict, etc., organized a network called “no bass net”. However, it is still very difficult to reach the satisfactory results in most of the water bodies in spite of intensive efforts, and there are many issues and problems to be modified, improved, or solved. Here, I will review these attempts and show some of the issues and problems, anticipating to have constructive comments and suggestions.