Abstract
The auditory characteristics of pelagic fish have received less attention compared to those of benthic or freshwater fish species, even though underwater sounds are considered to affect their behavior. Audiograms of five spotlined sardines were obtained using the auditory brainstem response technique in which the evoked potential on the skin covering the head of the fish was measured. The auditory brainstem response is a non-invasive electrophysiological method that enables the auditory threshold level of fragile species, such as spotlinedsardines, to be measured. The gas bladder of the spotlined sardine has been considered as possibly contributing to an enhancement in their hearing. In the test, the sound absorption profile of sardines was also measured. The frequency at the lowest auditory threshold level (i.e. the most sensitive frequency) and absorption were foundat 1024 Hz and 1040 Hz, respectively. The spotlined sardine was found to be sensitive to sounds at relatively higher frequency ranges compared to other seawater fishes and the gas bladder is seen to play a significant role in detecting sound.
