PURPOSE: To inhibit fishery product from penetrating the raising area by providing two electrodes placed underwater, a shield conductor disposed therebetween and surrounding the raising area and a power source for generating electric screen applying different potentials to the electrodes.
CONSTITUTION: A power source 3 for generating electric screen applies different potentials to electrodes 1a and 1b to cause the intensity of the electric field inside a shield conductor 2 to be zero or extremely weakened, that in the inner space between the periphery of the shield conductor 2 and the electrodes 1a and 1b to be strengthened and that in the space between the electrodes 1a and 1b, the space being the upper part of the shield conductor 2, to be relatively weakened. Therefore, when fishery product living in the vicinity of the bottom of the sea tries to penetrate the raising area S, the space having intense electric field between the shield conductor 2 and the electrodes 1a and 1b inhibits the penetration. While, when they tries to penetrate there from the upper part of the shield conductor 2, the space having weak electric field between the electrodes 1a and 1b upper part of the shield conductor 2 inhibits the penetration. The penetration of the fishery product to the raising area is thus inhibited without fail.
MAEHATA HIDEHIKO
TSUKAHARA MASANORI
DAIKU HIROYUKI
SUYAMA HIROYUKI
OTANI SEIJI
