MEPS 466:225-232 (2012)  -  DOI: https://doi.org/10.3354/meps09933

ABSTRACT: A growing body of evidence suggests that larval fish use sound as an orientation cue to remotely locate suitable settlement habitats. Several theoretical models have used hearing thresholds to estimate the distance at which fish larvae can detect reefs. However, researchers have often measured hearing thresholds from fish raised in aquaculture environments, or held them in closed-system tanks once caught, where equipment can significantly increase the noise levels in the tanks. The possibility arises that exposure to such noise negatively affects the hearing ability of the fish held there, such that distances predicted from these studies may be underestimated. The objective of this study was to compare the hearing ability of wild versus aquacultured snapper Pagrus auratus using auditory evoked potentials. Juvenile snapper from aquaculture tanks had significantly higher hearing thresholds at 100, 200 and 400 Hz than wild snapper. A controlled noise-exposure experiment, where snapper were exposed for 2 wk to low-intensity noise at 120 dB re 1 µPa, confirmed these results. When plotted using an extended reef-based model, the distance at which aquaculture-raised snapper are predicted to detect a particular reef was half of that found for their wild counterparts. Clearly, the acoustic history of experimental subjects is an important consideration when using hearing thresholds to make ecological estimations, such as the distance at which larvae could detect reefs.

KEY WORDS: Fish hearing · Orientation cue · Threshold shift · Aquaculture noise · Auditory evoked potential · AEP · Pagrus auratus