A Mirror Image Of Blackbass Conservation: Active Control Of Blackbass As Invasive Species In Japan

Largemouth and smallmouth bass, Micropterus salmoides (including M. salmoides floridanus) and M. dolomieu, together with bluegill sunfish Lepomis macrochirus, have been designated "Invasive Alien Species" under the "Invasive Alien Species Act" in Japan. A variety of attempts have been made for the effective control of these fish, including the employment of electro-fishing vessels, the artificial control of water level in reservoirs, and the development of "artificial spawning grounds", devices into which spawning is induced for subsequent disposal of the eggs. Electro-fishing vessels, generally prohibited by the "Act on the Protection of Fishery Resources", have been used with special permission in many water bodies, including the moats of the Imperial Palace in Tokyo and in Lake Biwa, for effective collection of largemouth bass and bluegill. In a set of reservoirs in Fukushima Prefecture, a stepwise draw-down of water level has been tried in an attempt to effectively dry out their spawning sites. Various models of "artificial spawning ground" have been used successfully in several reservoirs and ponds to induce spawning of largemouth bass, thus expediting effective control of its reproduction. Here, I will introduce examples of these techniques for suppressing populations of invasive fish, as a mirror image of policies adopted for water bodies in which black bass are to be conserved.