Abstract
In a marine ranching project in Kagoshima Bay, HeNe-laser (633nm in wavelength) is planned to be used as measures of fish control. As eyes of marine fishes seem not sensitive to this wavelength of which attenuation is high in sea water, the capability of the red sea bream in detecting the laser beam was examined electrophysiologically. While a low sensitivity of the fish eye to the light was indicated by S-potential, the cardiac response of the fish to the visual stimuli of the laser beam, in sea water with suspended substances of 3ppm, revealed a very low thoreshold; 15-8.6μW in 300lx, 2.8μW in 10lx, and 0.24-0.14μW in total dark. The results showed that the capability of the fish in detecting the laser beam was much higher than the man's, and that the HeNe-laser could be used in the project.
