THE ATTRACTIVE EFFECT OF FEEDING SOUND TO JUVENILE GRASS CARP CTENOPHARYNGODON IDELLUS

To assess the effect of feeding sound on behaviors of juvenile grass carp (Ctenopharyngodon idellus), the recorded underwater feeding sounds of natural food Lemna minor by 10—15 cm body length grass carps were played back to the experimental fish in phonotaxis experiments. The fish swimming behaviors and distributions in the experimental tank after exposures to different sounds (pure tones 500—3000 Hz and the feeding) were investigated in a fibreglass tank using no sound playing as a control. The results showed that the fish exposed to the feeding sound had the highest swimming speed towards the sound source after 3 minutes and the longest sojourn time in region 4 & 5 closest to the sound source, while the fish exposed to the pure tone had same swimming speed towards the sound source and same sojourn time in region 4 & 5 as the control. In the 20 minutes of playbacks, the fish exposed to the feeding sound had the highest average swimming speed and the longest time of distribution in region 4 & 5, compared with the control and the fish exposed to the pure tones. Our results indicated that feeding sounds had attracting effect on juvenile grass carps. These findings provide scientific basis for acoustic attracting fish.