Allis shad (Alosa alosa) exhibit an intensity-graded behavioral response when exposed to ultrasound

Most fish cannot hear frequencies above 3 kHz, but a few species belonging to the subfamily Alosinae (family Clupeidae) can detect intense ultrasound. The response of adult specimens of the European allis shad (Alosa alosa) to sinusoidal ultrasonic pulses at 70 and 120 kHz is tested. The fish showed an intensity-graded response to the ultrasonic pulses with a response threshold between 161 and 167 dB re 1 microPa (pp) for both frequencies. These response thresholds are similar to thresholds derived from juvenile American shad (Alosa sapidissima) in previous studies, supporting the suggestion that these members of Alosinae have evolved a dedicated ultrasound detector adapted to detect and respond to approaching echolocating toothed whales.