Electroretinograms and Spectral Sensitivity in the Ayu, a Salmonoid Fish

Abstract

Electroretinograms (ERGs) were recorded from the eye in situ of immobilized ayu, Plecoglossus altivelis. The light-adapted ERG was characterized by a small a-wave and a distinct b-wave, while the dark-adapted one was dominated by b-wave. Domination by b-wave was also observed under adaptation to 1 lux. During dark-adaptation, transformation of ERG took place within 5 min, although full adaptation required 30 min. When adapted to dark or 1 lux, the response became maximal between 497 and 525 nm, decreasing more gradually toward longer wavelengths than toward shorter. In contrast, the wave form varied with wavelength of the stimulus under lightadaptation, which is probably related to color discriminating capacity of the fish.
Spectral sensitivity curves in terms of b-wave amplitude were constructed and their significance was discussed.