FLOUNDER SHOW CONDITIONED-RESPONSE TO 200-800 HZ TONE-BURSTS DESPITE THEIR CONDITIONING TO 300 HZ TONE-BURST

As a part of a marine ranching project, this study examined responses to tone-bursts of different frequencies by flounder juveniles which ha d been conditioned to come to a sound source of 300 Hz tone-bursts in a fish cage. After completion of conditioning, the flounders showed th e conditioned responses to 1 s tone-bursts of frequencies of 200-800 H z with a peak sensitivity at 300 Hz, and a slight and short response t o a continuous sound of 300 Hz immediately after the sound projection, coinciding with the previous finding with res sea bream juveniles, Th e bimodal pattern of sound frequency-pressure threshold concluded that this conditioned response was mediated by the inner ear in response t o particle displacement. This pattern, however, was different from a r eported audiogram with a peak seak sensitivity at 100 Hz, probably bec ause of the effect of frequency of the conditioned sound.