Field assessment of behavioural responses of southern stingrays ( Hypanus americanus ) to acoustic stimuli

Abstract

The ability of elasmobranchs to detect and use sound cues has been heavily debated in previous research and has only recently received revived attention. To properly understand the importance of sound to elasmobranchs, assessing their responses to acoustic stimuli in a field setting is vital. Here, we establish a behavioural audiogram of free-swimming male and female southern stingrays ( Hypanus americanus ) exposed to low-frequency tones. We demonstrate that female stingrays exposed to tones (50–500 Hz) exhibit significant changes in swimming behaviours (increased time spent swimming, decreased rest time, increased surface breaches and increased side swimming with pectoral flapping) at 140 dB re 1 µPa (−2.08 to −2.40 dB re 1 m s −2 ) while males exposed to the same tones did not exhibit a change in these behaviours until 160 dB re 1 µPa (−1.13 to −1.21 dB re 1 m s −2 ). Our results are the first demonstration of field responses to sound in the Batoidea and show a distinct sensitivity to low-frequency acoustic inputs.